You got me on the 5" spacer??? anyway with the 700R4 the best performance upgrade would be to change out that 3.08 and install a set of 3.73's. Calculations show with your tires....3.08 = 2069 rpm
3.73 = 2506 rpm
or even a 4.11 = 2761 rpm ....you would still be able to cruise all day long, my pick would be the 3.73 or something close.