Nope...the only thing different is the pistons...the GT's are a higher compression...the rods and crank are the same.
Since your top end is still good, remove it and clean it up good...might as well port your Supercharger while it is off too. If you do plan on high compression your going to be needing a tune and no WAY your going to be able to drop to a 3.5" or 3.4" with just a DP and other small bolt ons. 3.4" on a high compression build is nearly a 3.1" on a low comp. L67. Keep the stock pulley...you don't need a lot of boost to get power with a L36. If it is your DD then swap the L36 block in, port the S/C, get a 180*, Autolite 104's, 3" Downpipe, Custom CAI/FWI, and a tune...TUNE IS A MUST.
Just putting it out there. Hope you get it done.
