Dodge Ram 50 Trasmission Shift Problem

I bought a 91 Dodge Ram 50 a few months ago and I knew it had a bad
trasmission in it. I had a friend overhall it for me and it now works.
The last week or so it seemed to wait until a high rpm before it would
shift from 1st gear to 2nd, and 2nd to 3rd. after the first time of
shifting it would then run fine untill it was cooled off. Today when I
drove it it waited untill extreamly high rpm before it would shift the
first time, and again after the first time...shifted perfectly after
that.

is this a simple fix or does it mean pulling the trasmission out again
and doing something?

Thank You.