Freestyle lowering compression

[lakeboy183]

i am buying a new ski and the engine runs on av gas and i dont want to deal with going to the airport to get it.. so i want to lower the compression,, the engine has a ada head and able cylinders.. the guy told me i could either cut the existing domes or buy higher cc ones.. what i would like to know is if i buy new domes will any ada domes work or will they need to be custom made/cut for this engine. it is a 820cc 5mm stroker

thanks.. Nolan