Go with a 402 (4.000" stroke/6.3L) or a 421 (4.125" stroke/6.8L) stroker kit with flat top pistons. With the right heads, cam and intake you'll easily exceed 500 rwhp with the 421.
Better start saving for drive train upgrades as well.
What's the cost associated with stroking a motor?
Performance:230/232 .614 .602 114 cam,Kooks 1 3/4 headers/catted mids,Spintech,CSP ported intake/tb,UDP,tune by CSP.
Suspension:Pedders big bore shocks,GSR II struts,Lovells RR bushings,Kings 0 drop rears/20mm drop fronts.