Does anyone have dyno numbers or 1/4 mile times on a 355
running an XE-268.

 

A 350....

That covers alot of ground.

What heads? Exhaust? Intake? Gears? Weight? etc.

 

I am considering changing from my H-272 to the Comp Cam XE-268.I have Dart Sportsman II heads and intake,750 holley,1 5/8
shorty headers,true duals,corvette converter (700r4)and 3.73
gears.Car wieghs about 3600lbs.I`m looking for mid-low 13`s.
I was also wondering if my money would be better spent on a
2800 stall converter or better headers?

 

I believe I would fix what ails the car before just up and swapping parts for other parts that aren't really a whole lot different.

Your exhaust isn't doing you any favors. Get some 1¾" headers, and make sure that the rest of your exhaust actually flows decent. Just because there's 2 pipes doesn't necesarily mean it's better than 1 pipe. That would especially be true if your duals are custom bent up at a muffler shop on the usual machine that crimps the inside of the bend; do that to a 2½" pipe, and you end up with a cross-sectional area about the same as a 2" pipe.... pretty constipated.

Get the car dyno'ed. That will show you what the power curve is. That can be real informative.