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doing a dirt cheap rebuild on a 400 big block.

I'd suggest what Jwilli/forforty said plus do some home porting on the 516 heads if you have em. Reportedly the 516's need to be ported by someone experienced with their intricasies or flow can be hurt for a high perf build but for your app I'd home port em conservatively. On the balance you can get a gram scale at HF on sale for 9.95 & it's just as accurate as my buddys high dollar one. You can remove material off of the rod small end as needed since the piston/rings/pin/locks go together with the rod small end weight for reciprocating weight in the balancing formula & just get the rod/piston C to C big end/small end "holes" fairly level for accurate weighing plus with the steel being heavier less mass needs to be removed to achieve the same amt of weight. Weigh what you have & go from there

live every 24 hour block of time like it's your last day on earth