So rather than argue over 5bhp that is probably just dyno differences I'll just answer your questions;

Personally I wouldn't run an 010 card on unleaded fuel full stop, if HRC thought it was OK they'd never have made the 030 card but if you must try it (and a '28 on the std card and flywheel will never make near 60bhp, Tyga put a '21 flywheel on, a modded airbox, fancy reeds and rectifiers and only got 58, dyno graph here ) then you probably want to go to at least 170 if you're just going to change the main. If you're buying the jet kit and plugging the powerjets I'd put the 200's in to start off, it will run, wheather it will die if held flat out or not is another matter and if you're not going to hold it flat out why bother changing cards?

Plugs? BR9ECMs or BR10ECM's

OEM pistons are fine
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Please do not PM me technical questions, if you can't find it on the Forum start a thread