I am going with a set of 70 390 291c's for my 343. There is some work that needs to be done to the combustion chambers as they came off an AMX that broke something and whatever it was bounced around in the cylinders and chambers, and this resulted in "pits" and gouges around the edges of several of the chambers on the spark plug side of the chambers. My builder says he can blend the damged sections and that it isnt going to affect anything. The gouges are on the edge of the chambers on the spark plug side at the small section of the chamber that is squared, the horizontal edge of the chamber that protrudes into the chamber a tad.
To me on one of the chambers it looks like in order to "blend" the pits you would have to just about remove that horizontal sqaured section of the chamber. Now I know this machinist well and he is the best around; builds tons of hi-po motors and has built several of his own AMC's including a 420 Cu In 401. How much compression is it possible to loose by blending the horizontal sqaured section of the chamber on the spark plug side. The gouges look like someone took a 1/16"-1/8th" round file and made "slots" appox 1/16" inch deep on the edge of the chamber on that sqaured off section adjacent to the plugs that protrudes slightly into the chamber. IT is only on one head and I only paid 100 for the pair.

He milled them already and they look fantastic otherwise. Please advise. I was going to get the edelbrocks but jumped on these and plan to spend the residual on a roller cam set up for my 343.