Using 8 3/4 with /6

Keeping the same rollers? I had 3.55's & an 8 3/4 in My '72 swinger, w/235/60HR14 tires(about 25.2" dia.), & the correct speedo pinion my slanty topped out at 118mph. That
was w/a stock torque converter. Your tires look taller, and your intake system capable of more top end than my 2bbl setup.