Alloy Heads

58cc is going to skyrocket cylinder pressure on a flat top zero deck. I'm at 61-61.5cc-ish with .011" from zero deck flat tops with 5cc valve reliefs, .028" gasket on a .030" over 'teen and that puts it up at 9.65:1 min.

The same outfit on a 360 stock crank goes 10:1 A 390 stroker is going to put you well above 10.5:1.

I don't know how spendy your fuel is, but with a 58cc closed chamber, you might consider pocketed face valves, reliefs in the pistons to accomodate lift and help CC increase and get some Cometic gaskets at .039" to keep quench and keep it sealed, but bring cylinder pressure back down to Earth.

I would leave the cam at 3°adv.