[TurboKraft]

Those heads will need machining (aka flycutting, decking, etc. ) to clean up the sealing surface. Remove *as little as possible* from all 6 heads evenly. No head gaskets.

Check the cylinders as well, they may need minute clean-up machining.

Twin-plug: it's one of those things to do if you're already porting and overhauling the heads. Even if you cannot do the rest of the twin-plug conversion right away, just grind the electrodes off an old set of plugs and install them in the lower holes until you're ready. Then it's all external bolt-on conversion stuff, no going back inside the engine.

PM'd you about the porting, cams, etc.
Sport-SC aka SC330 works fantastic with basic 7:1 CR pistons, helps liven it up. Seems like when we have sent Elgin any OEM 930 cams, the answer is always "no" when it comes to re-grinding, and he supplies new. Not cheap, but high quality you can trust to be consistent.