I have a complete 340 casting date 7-7-69 has 1 X and 1 J head on it has edelbrock preformer,has a cast crank turned 10/10 and a '73 340 balancer not stuck turns easily,has what looks like the later 340 pistons with the 4 valve reliefs. the bores miked at 4.06 ish so I assume its std but worn.I...