MR is midnight runs it's an ottawa street racing board!
I think 3.73 is a better gear and you will still keep your top end!
My car is 4 speed auto and with 4.10's it will rev at approx 2400rpm insteadof 1750rpm at 100kph so it should not be too bad, besides my bud has an 88 GT with 3.55 and he likes them but he said that there was not that big of difference from the stock 3.08's.
my suggestion is go with the 3.73's but I'm not a mechanic
ask TKM he knows his stuff especially with stang's!
His phone # is the shop section under TKmotion ask for Tom