I just aquired what I thought was a 58 292 with ECZ-G heads. well the heads are good ECZ-Gs but the block bore measures about 3.665" which should be a tired 272 bore. the casting nubers are as follows...pass. side of block-ECG60150 (or the 0 is possibly a C) , dist.area- 26 ECG Dif , main caps- EBU-6328-B . should this be a 272? and how far can I safely bore this block. I also have a late 292 block in the garage as well,should I just use the late block instead? thanks for the help!