Thanks for the tip, you were right I had the cable much too loose from seat of the pants adjustments. Disconnecting the ball socket and adjusting correctly helped smooth the low throttle shifts, although now my car is pretty much in 4th from 30mph onward.

1-2 and 2-3 are still pretty harsh, no where near as smooth as a modern automatic unfortunately; but with the fluid fully warmed, not too bad either. I'll keep tweaking I guess.

Just wanted to give credit where it was due, apologies for being dismissive at the time.

Cheers