Would an extra lug make that much differance? The easiest thing would be just getting stronger 4 lug axles. I've already got a brand new Motorsport 28 spline 4:10 set.
I'll be cranking around 500 hp.
if youre sticking with welds, theres really no reason to go 5-lug. most people do it just for the better brake options and classier new-style wheels. for a drag only car, 4 lug will be fine.