consider the price of 30spline chromos... your in the ballpark for a set of 30 spline RCVs. now, your ring and pinion are DEFINANTLY going to be your weak link. a full case locker like an ARB or OX, truss, and stout diff cover will do a lot to help ring gear deflection, which is the biggest killer of D30 gears when running tires that big.
personally, i wouldnt gear a D30 to 4.88, id stay 4.56 to keep that 3rd pinion tooth in contact with the ring gear.
regardless, itd be a pretty bling 30, very polished turd.