Mmmmmm...... Backwards logic..... 8.5 is (marginally) OK for casual drag racing since you will rev the crap out of it everytime you launch and can use a high stall TC to get past any low RPM 'dead zone'. Low CR on street/driver use is only OK for grandma going for groceries, or hauling logs. 8.5 is 8.5, nothing better and DCR will be the mid 6's which is below the DCR of a stock 318.:eek:
Edit to add: You mention getting down to 57 cc's; that would be an interesting approach..... put the $$ in milling and save $$ on pistons. Assuming pistons .075" down in the bore, flat tops, and .028" thick head gaskets, you're around 9.25 SCR, and DCR is now back up to around 7.3-7.4 with that cam. Keep in mind that when you mill that much, then milling the intake side of the heads may become necessary (more cost), AND you are going to possibly push the heads down far enough that the pushrods might be a bit too long. With some tricks, you may be able to get past the pushrods (IF it indeed any issue, which it may or may not be; it's a case-by-case thing, and completey dependent on the individual parts). That may be your lowest cost approach and forget any piston/rod changes.