welcome aboard Darren.
what part of VA?
I have a running LS / T56 combo, although the chassis is a one-off - a modified Rotus chassis.
TKO will save you a bunch of weight, and probably some room. The engine was no problem in mine, but tranny is TIGHT. The disadvantage, as you point out, is the T56 is already in your hand, and the TKO will require some $$$.
Coincidently, at Carlisle yesterday, Burton automotive had a LS3 powered Stalker. I think Dennis told me his finished car, complete with a bunch of radio equipment and roll cage (it was a customer car) was 1600 lbs, which is 150 lbs lighter than my Rotus. I suspect pretty much all of that weight is in the worst place possible in my car... wheels, tires, brakes, and axle.
I'm in Maryland, so if you're in NoVA, relatively local.