have87 iroc p.o. pulled orig 305 and put in unknown 305 shortblock w 416 heads.no one has been able to find #'s on this block.several have tried.my problem is i think its atruck block pulls to 4k and lays down until shift then pulls hard again.w o pulling intake i have no idea of flat tappet or roller.would 1:6 rockers improve this at all?thanks.still has orig. tpi setup.

 

The block casting #'s are on the surface behind the heads and above the bell housing mount. Look there. Sometimes the last three digits of the casting # are cast into the side of the block (that's all you need to identify the block).