The 305 AS with 350 gaskets is should not be legal. The bigger bore gaskets may unshroud the valves a bit and increase low lit flow.

I have the customer that wants to make sure that his engine is under the limit . I advised that i expect it to be over by around 1.0 compression value. Stacked MLS gaskets can reduce that value to the legal limit.

I will have him send a letter and just put this together as is , as it has been run for 15 yrs.
If somebody on the board can respond with a valid answer ,it would be nice.
Thanks, MM