I'd start with a roller block and run a hydraulic roller cam with OEM lifters.

streetable, displacement is always your friend. if your mag heads are untouched, opening up the pushrod pinch, doing some bowl blending after taking the valve job out to actually fit the 1.92/1.625 valves (the OEM VJ is typically about .030" undersized for those valves), and do a little valve guide boss profiling, and your current heads will support 425-450 HP.

if this is a budget build, I'd pick up a mag 360, keep the stock crank and rods, use KB107 pistons, do the aforementioned port work, use hughes 1110 springs, and get the roller cam reground by bullet cams, and see if they can fit the HR272/340 lobe on the core, using the same lobe for intake and exhaust. you may need to cut the valve guides down some for seal/retainer clearance with this much cam.

I'd be tempted to try the Scorpion Performance AMC pedestal mount rocker kit on the mag heads, too.