The combustion chamber is tricky, you have to maintain your squish area but that corner near the middle of the chamber could use a little blending (don't go overboard).
Look at the "heart shaped" chambers in good heads, you want something like that but I don't think its possible with iron heads unless you have N351s.
When people build a race engine for a supercharger, often they reduce compression to increase maximum boost levels. I've heard of race engines running 7.5:1 and maybe less but with really big boost.
With a stock block the ideal is just to keep it low enough that you can add boost until you reach your power goal. A stock block with 8psi gets real close to that point which is why so many people go that way, its easy and it works.
Going to a head with slightly bigger chambers just allows you more boost potential.
Its always better to run more boost with a conservative tune than less boost and an aggressive tune.
Another way to think about it is that your fuel/air mixture can only be compressed so much before it detonates and a high compression motor just has a smaller combustion chamber volume (by smaller chambers or piston domes), so if the total pressure in the cylinder remains the same (trading compression for boost), the low compression motor can hold more fuel/air mixture in the chamber without detonating, that means more power potential and if actual power is held constant, the low compression motor gets there with a more conservative tune.
I wouldn't worry too much about old pistons, aluminum does not oxidize as rapidly as iron, if they were not abused and the bores can clean up with a hone, the pistons are probably OK for a re-ring (ask your machinist).
If you want to prep your stock heads, I know there are some "stock" racing classes where "stock" fox bodies run 11's in the quarter with cast iron heads, search for what they do and copy (but they probably cherry pick heads with small chambers, you want to go the other way).
