Rims / Tires for my 1969 Corvette

[Dave Rifkin]

Here is where I am so far;

American Racing T70 (15 x 7 front, 15 x 8 rear)

BFG Radial TA's 255/60-15 for the rear and I was thinking of putting either 225/60's or 235/60's on the front. The issue I am having is the stock size 225/70-15's would have a diameter of 27.3". The 255's have a listed diamter of 27.1" (close enough); should I be concerned with the diamter of the fronts? The 225's have a listed diameter of 25.6" and the 235's have a listed diamter of 26.1"
I don't want the speedometer to be way off with the varying tire diameters.

I think if I can get this figured out I can pull the trigger and order my new rim/tire combination this weekend.