I've had some inquiries about cheap Pontiac blocks. Prices can be high for the ones I've quoted because they are high demand codes. If you want a complete 400 for rebuild here is a cheap candidate. LINK: http://cgi.ebay.com/ebaymotors/1970-81-P...1QQcmdZViewItem
More often than not the later blocks will fit the first gens, it's the early motors going in later cars where you usually have the issues. Always exceptions to the rule... and as Jim mentioned there are always ways around it if you do find an oddball...
I've found quite a few good candidates as of late. I know a few who part out Big cars and use them for Derby cars... they sell a good running complete motor for about $250. You just have to have the space to store em lol...
I have a couple 400's ('77's?) and a 350 (Yj, D228, cast 9790079) I could let go cheap. They are builders and I have to check the condition. They would only be cost effective for pick up in NW PA.
I just saw a 71 400 2bbl--complete with all acc except breather and carb. A buck seventy five seems reasonable. The issue is more storage and transporting the engine issue than money; otherwise, there is a good chance I'd scarf it up. This is its last chance, and in another few months, this is yet another that goes to china as a brick of metal.
If you ship it as "scrap" (I forget what class that is defined as)it wont cost a WHOLE lot to ship it on a big truck. It will have to be void of all fluids AND you may need access to a shipping dock that it can be left at, or be able to pick it up at the trucking company's depot.