Ghost, here is a quick suffex code (right frt stamp pad, end two letters) for '57 Vette
EF FH EH FG EM FK EG EL EN
if it's one of these, I can give you the HP etc.
Also someblocks were carried over to '58 (and some truck apps) '58 vette suffex
CQ CT CU CS CR DH DJ DG
If you happen to get a match, price just went up!