Just wondering, what improvements have you guys ACTUALLY seen from half fill, meaning you guys pushing big power, have you seen 340 blocks before and after half fills with noticeably less block distortion?

The reason why I ask is because my engine is almost finished and my machinist was trying to talk me out of the hardback the other day. I know that he knows his stuff, but he is a huge Windsor guy with a whole bunch of NHRA records but not really a hard core mopar guy. He was telling me that with the meat on the 69 340 block I have, he thought I'd be OK at the power levels I was looking to hit (650- 700fwhp max with the procharger) without using the block fill. He didn't think it would be helping to much with bore distortion and he said that with the .030 overbore the block was still pretty strong. I told him I still wanted to go ahead with it just for the peace of mind if nothing else.

I know guys here have seen the before and after effects of filling the block though, do you guys think on a stronger LA block like a 60's 340 that it would be helpful to do for a big power/lower RPM boosted setup?

Currently I have main studs, hughes girdle, factory main caps, Eagle H beam rods and a factory forged crank.