1) Are You proposing LS SBC/SBF/MagnumSBM style rockers, or actual ball-stud rockers which require guide plates? FYI, BBC rockers are closer to the stk. SBM dimensions, & common with desirable ratios.
2) If You use keyed-base pedestal-style rocker, You could easily cant the intake valves, allowing for better numbers & widening the upper port.
3) If You raise the VC rail, and cast/machine the heads to raise a std. Intake 1/4", that's a big plus, with only maybe custom china wall seals as a special part.
4) Are the plans for flat-top slugs at zero-deck, with valve reliefs? Stock Magnum slugs, or?