i was running a 3.14:1 diff and 215/45/17 tyres, which upped the speeds to get 40 mph out of first, 70 odd out of second and 120 out of third, 4th and 5th gears though were purely crusing gears as you really couldn't drive in them up hills on the motorway

i found that sticking an 8 x 17 rear wheel with a 45 offset filled that rear arches perfectly with those tyres and no scrubbage either

with your standard 3.92:1 diff as found on the twinkys you should be able to get a better cruise out of it