I was looking for a drill bit that size and none was to be found. I found that a 1 and 3/8 metal cutting hole saw will do the trick. Cost me $6 at Napa. But I think they was also wanting to get rid of it. If any body would like I could get the part number.
For the distributer spacing I used to 1 and 1/4 inside diameter washers from napa. They're marked 1 and 1/4 but they're actually 1and3/8. Put two of them together and you'll get your 1/4 inch height. Alittle Jb weld and she's perfect.

This hole doesn't have to be perfect as you'd might expect. There's an 1/8th inch clearance between shaft of the distributer and the actual old tpi intake.
You could actuall drill out the hole too big and then Jb weld the washer where you'd like b/c that's what the distributer will sit on.

Not that anybody cares but,
I just thought I'd save ya alittle time and money.

Looking to get ole 406 going the 1st.
happy holidays!

 

Great find!
Thanks for helping people make this cheap mod even cheaper. That's what the LT1 intake is all about.

 

ARE YOU SOME HOW ADAPTING THE LT1 INTAKE TO A REGULAR ENGINE SETUP IF YOU ARE I AM INTERESTED

 

Checkout John's Tech Article here:

http://www.sethirdgen.org/LT1.htm

Then do a search here cause some of the guys have found out some newer things and parts to get as above.

 

I ended up going to a tool rental place in town. I got the 1/2" tap, drill bit for the tap, and a 1 3/8" bit for $60 (all new pieces). I can return them at any time and get 1/2 my money back.