[DeadheadNM]

I’ve got a th350 in my Blazer and a 700r4 in my K20 with 3.73 and 4.10 gears respectively: both with 350 sbc and 33” tires. The Blazer with that driveline/tire combo drives fine to 60-65mph. The k20 with 700r4 will cruise nice at 75mph. There is very little clearance at the front shaft yoke in the k20.

I recommend keeping a th350. It’s not worth the hassle and added expense to swap in the 700r4. If I were to redo my k20 I’d likely make use of a th350 with a gear vendors overdrive. My Blazer has its original drivetrain and my k20 has a correct 350 or I’d have entertained an engine swap.