74 Duster 408 Daily Drivability with 3.73 Gears Vs Stock 3.21 Question.

I just finished installing a 408 and a 46rh and 3.55s . Only driven it about 8 miles but I gave it a quick 1/4 throttle from a stoplight and it boiled the rears . My tires right now are just 205/70-14s Michelins but it had plenty to turn a bigger tire .
55 mph @ 2000 rpms !
My plan is to go to a 225/60-15.

Engine is a mild build with a 221/229 - .550 (1.7 harlan Sharpes ) on a 112 .