[bowtieguy79]

If you are choosing the 4L80E they are a power robber, based on gearing off the line. Make sure you compensate your rear end gear to offset the trans tall first gear.

I would get what your budget allows for, and plan on a cam swap regardless of engine size!

I put a LQ9 in my 72 Sub with the 4L80E, my rear end is 3.07, its a pooch off the line, but at 60 it pulls very hard. I put a decent size cam in it as well. I'm going to go for a 4.10 this next winter, should take care of the poochy-ness.

Do what is best for you! Good luck!