I'd retain the rear as is because while 3.73 will be nicer on the highway - it's not as nice as a 4.10 with 700R4 O/D, which makes your 4.10s a 2.87 at highway speeds - and retains the exact same current acceleration performance in 1st-3rd that you have today. I'd get built 700R4 though, not a junkyard swap, because 4.10s can be kinda rough on it if you do the occasional burnout...
