2-3 bad shifting

I got a 86 ranger 2wd. I put in a 302 with a c-4 tranny. I did a complete fluid and filter change, including fluid in torque converter. Had to install new vacuum modulator due to leaking. Seems the transmission shifts too soon and between 2-3 the engine revs way up for 1-3 seconds until it shifts into 3rd. It doens't slip in any of the gears.

Is there a way to adjust the shifting and why would the engine rev high between 2-3.

Also was considering putting in a better torque converter. What do i look for, when i buy a new one.