Magnums will only add more cost, the cost of buying them and all the crap to make them work. mill the 360 heads down to 57cc and run them.
its .0048 removed per 1cc.
I have milled those 360 castings down to 55 cc no problems, kust dont forget to mill the intake and or intake side of the heads, when removing that much i like to split the diff between the heads and intake so that the valve cover rail doesnt get too thin.
If u van keep the rhs hesds and just sell he short block....that would work too, but ull still wanna mill them down to get a comp ratio with those sealed power pistons....and the stroker will bring more money with the heads on it.jmo