I am installing a new dist. and wanted to double check tdc so i installed my new proform piston stop and with it screwed all of the way in it never touched the piston. I have never used 1 before so am i missing something??

how did you bring the piston up to the stop? with the starter?

If your heads have a spark plug hole that orients the spark plug straight across the combustion chamber parallel to the piston top, then the piston stop will never contact the piston and stop it.
You'll probably have to fabricate your own custom piton stop.
3/8" length of steel tube and a old spark plug and a welder is all you need.
knock the center out of the old spark plug so you just have the steel body.
weld the steel tube in the spark plug at a slight angle.
Leave a bit of a length on the business end. You may need to bend the end slightly so it will point down and contact the piston top before reaching TDC.
You may need to adjust the length and angle of the probe end. Trim the other end of the tube off.

Loosen off both rocker arms completely on # 1 cylinder so that the valves are completely closed and will not move. Move the piston away from TDC.
Mark the body of your piston stop so you can see what direction where the probe end is pointing. Screw the piston stop in the spark plug hole so the probe end is pointing down. bring the piston up by rotating the crank BY HAND SLOWLY so it just touches the piston stop. Mark the balancer, Rotate BY HAND in the other direction until the piston contacts the stop again. Mark the balancer. TDC is exactly in the middle of your marks.

Your car was running and you want to install a different dizzy?
If thats the case, then all you need to do is take of the dizzy cap( leave all the wires on if you can) and mark on the motor where the rotor is pointing. Then mark where the connector for the module is . Then remove the dizzy, the rotor should turn counterclock wise an eighth to a quater turn, mark where the rotor points now.

Ok grab your new dizzy. Line the module connector up with your mark, then line your rotor up with the second mark. the dizzy should drop down, if it doesnt give the rotor a little jiggle. The rotor should now be lined up with the first mark. If it doesnt pull the dizzy up and rotate the rotor a tooth, then drop it back down. Do this untill the rotor points to the mark. If you get to the point where you cant get the rotor to line up exactly, just get it as close as you can.
Put your new cap on, and one at a time put the spark plug wires on.
Start vehicle and adjust base timing as needed.

The only reason to need to find tdc on number one, is if the motor was turned while the dizzy was out.

You don't need a piston stop to change the distributor.

To use a piston stop, you need to remove the rockers from that cylinder before installing the stop. The valves will hit the stop and damage it. With the stop installed, you then need to install a degree wheel to find out at what degree of crank rotation the piston hits the stop in both directions by turning the engine over by hand (not with the starter). Once the degrees are found out, the piston stop is then removed and the crank is rotated to half way between the 2 degree marks. The piston is now exactly at TDC. About the only reason you need to do this is to see if the timing mark on the balancer lines up with the pointer when the piston is exactly at TDC.

To change your distributor, bump the engine over until the timing mark on the balancer lines up with the pointer. Pull the distributor cap off and look to see where the rotor is. It will be pointing to #1 or #6 plug wire. Remove old distributor and drop in new one with the rotor pointing in the same place. That will get you close. If you then pull the rotor off, you can see the magnetic pickup. Line up the pickup points and clamp down the distributor. That will get you close enough that the engine should fire up to set the timing better.

I am installing an msd e-curve dist., gm serpentine system, balancer, headers and an engine rewire. I just wanted to double check the pointer.

"f-bird" that makes sense. These are aftermarket al. heads. I read all i could find about using a p.s. but i didn't see anything about it not working. I will break out the welder and make me one.

I did NOT use the starter. I bolted my rotating tool to the balancer.

Thanks for the replys. 1 more question.......

My new plugs, Accell 414s are about 1/8 of an inch longer than the ones i took out. How can i check to be sure they will not hit the valves or piston? I rotated the engine thru 1 complete cycle after i installed them and did not feel anything but i want to be sure.

The bottom end is a stock GW 350 and the heads are 64cc's

measure the plug reach. Some are 3/4" reach. Some are .708" reach.
Not the same. The plug won't hit the piston but the end plug threads (plug too long) or combustion chamber threads (plug too short) could be exposed increasing the chances of preignition.
What heads are you working with? Dished pistons? flat tops?

The .708" plugs are usually used in Fords and GM vortec heads.

I can't remember the brand of heads. I bought them from a speed shop in TN. for $850. didn't want to spend top $ for AFR. The pistons are dished.