The 366 has some useable part's if you can find a passenger/pickup bigblock block.
Due to the .400 taller deck height found in these block's,[to accommodate 4 ring piston's] the block is pretty useless [unless you want to build a stroker]
If you can find a passenger/pickup block, [shortdeck] you can use the crank, rod's, head's, pan, timing cover, etc.,a passenger distributor will be needed also, since the "truck" dist is .400 taller too. and build a "normal" bigblock.
366's share the same stroke crank as a 396, or 427. Truck rod's are good and healthy on the big end, compared to passenger rod's.
Pick up a book entitled, "How to build max performance chevy rat motor's" by Ed Staffel. Best damn book I've found for building a healthy Rat.
Include's casting number's of block's, head's, rod's, etc. plus how to calculate compression ratio's, porting on and on... A must have when building up a Rat. /forums/images/graemlins/shocked.gif