The adapters make it so the block will fit, no problem. You're going to need the later heads for brackets to all "line up" correctly. There's one bolt "hole" missing in the 389 heads.
Ed, where did you ever "hear" Pontiacs have bad cranks? Simply not so. In fact, the crank is the strongest part of the Pontiac. The block is the "weak link" once the cast rods are disposed of. Vinny Meyeda of SoCal, runs a 6.90s F/C with a 406 CID Pontiac with a factory nodular crank, spinning to 8,800 every pass. I don't "fool" with Pontiacs. I build them at the highest level (one 505 has produced over 2,600 HP). The 475 in Dirty Bird made 40 passes, shifting @ 9,200, without a single bearing or piston issue. The rod maker says that's all the rods are good for over 2,000 HP. And the same 8 pistons that were in it on the first pass, were in it on the 40th. How many blown/alcohol hemis and BBCs can "say" that, while setting new ET records at the same time? DB was the quickest Pontiac-powered car in the world for nearly 2 years. Still IS the quickest Pontiac "funny", and hasn't been down the track in over a year. The KRE crowd is encroaching, though. Bill Mellot's F/C went a 6.50 at Norwalk earlier this month. We're gonna have to drag it back out and put a "tune" on it, to move the "bar" out further. We'll see what Dave (owner) has in mind. "Catching" the Butler ProMod is going to be a chore, let me tell you! (6.27 @ 22, IIRC)
Virtually everything you speak of is obsolete for some 20 years now. With the advent of NMCA and muscle car "racing", developement of the ol' ***** has resumed, and they're "back" with a vengance. Afterall, can't have muscle car races without GTOs, and can't put Chevy motors in GTOs "just because", so the money flowed and the new parts came forth. Today we have a selection of blocks, heads, cranks, and everything else, that rivals that of BBF and MOPAR. At the last "Super Chevy" show we attended at VMP (2010), the quickest GM-powered car was a Pontiac (engine), not a Chevy. Dirty Bird had them ALL "covered". One of the exhibition cars was a ProMod with an 800" Chevy in it, and a BIG fogger system. We had him by .2 in the 1/8th. There WERE two ProMods with "Brad" motors. They had US covered by about .15. In the competition, Frank Gostalya's GrandAm (540 CID, single 4-bbl., gasoline, no adders) went 7.50s all day,very near 200. The only two Chevys that were quicker had 738 CID and big foggers. They ran 7.40s. Yes, things have changed a LOT coming out of Oakland County... Circle the wagons, boys, it's an ***** ATTACK!!!
PAX
Jim