what size bolts for tranny to engine block?

[crosby]

I have an 87 K20 (which happens to have an early 70's frame and axles), and I'm sticking in a fuel injected 350, mating to a TH400. I don't have the bolts that go through the bellhousing into the block, and want to be sure they're not too long (or too short). Anybody know how long they are supposed to be? It's not 100% where it needs to be, so I plan on using the bolts to finish lining everything up. The guide pins are almost in place, but there's about 1/4 to 1/2 inch of space between the block and the bellhousing right now. I still have to bolt up the torque converter and flexplate too, anybody know what size and length bolts I need for that? Should I use split lockwashers on the flexplate/torque converter? Thanks very much for any help you guys can provide!