1970 C10 Trans Issue after distributor upgrade

[rmawyer]

375 turbo hydromatic transmission acting strange after doing some engine work (upgraded to DUI HEI distributor and replaced spark plug wires). Transmission prior had smooth shifts at appropriate speeds but now shifts from 1st to 2nd at 45 mph / approx. 2500 tach and from 2nd to 3rd at 60 mph / approx. 3200 tach and shifts hard. Assuming something was missed or not put back properly during engine work. Any ideas on what to look for? Thanks for any help.