Questions on my 454

[Mammoth]

Hello. New member, I'm working on my 78 chevy k10 shortbed. Had a 350 with a automatic and the full time 4wd t.case. Putting in a decent 454 out of a 77 suburban and a muncie 465, and an np205 transfercase. Also had a 87 c10 doner truck pulled the hydro clutch and housing off. Im just freshening up my 454, seals gaskets, Etc. Im replacing the timing gears and the sets I keep getting are smaller!! The crankshaft gear bore no where near big enough to go on. Autozone stumped, napa said its a newer motor. IDK. Block numbers 361959 which is 73-85 cars and trucks, nothing special. Any help here? aftermarket crank maybe? I'm stumped.
Then after some research I've found out I cant use the SBC clutch, need a BBC because it externally balanced flywheel. It seems like a pain, but the 350 took a ****, and the tranny was on its last leg too. So it is my cheapest way out and think it gonna be awesome. Any help or ideas would be appreciated, I'm mechanically inclined, but mostly work on atvs and motor cycles. First time doing this type of swap.