Some additional info:
FEL PRO still make an american made gasket kit. Easily available.
MELLING make a high volume (25% more) oil pump. easily available
MELLING also make a oil pump shaft, but a FE billet shaft can be used if it is ground off slightly.... and it's a MUCH stronger shaft for a part that has some history of failure.
MAKE SURE that your builder/machinist understands how to bore a 10 degree deck offset. You can really screw up the block if they don't know what they're doing. Someone who does vintage engines, like the Pontiac 409 will understand the issues immediately.
For the most part, if you carefully rebuild these engines to stock, you have a strong strong engine. If you want performance, parts are very hard to find, like the Tri power manifold you see on some of these pages.
One last thing: I am not unfamiliar to engines, but this place is the real deal. There are some seriously experienced people on this forum, and they really know this engine. Most other forums I have visited only partly know them. Research what has been preserved here, and don't hesitate to ask questions... someone will get back to you, maybe not right away, but they will get back to you. I learned more here in a month than in a previous 6 months of looking around the net and talking to machine shops.
All the best, cool ride.
MEL Marine division... and if you thought MEL car parts were scarce....