3 on the tree conversion?

[egglestallion]

Hello everyone,
I'm new to the group. I've had great luck with other forums in the past to help me figure some things out. I just bought a 1972 c-10 and I'm looking forward to making it mine... For starters, it was originally a 3 on the tree and one of the previous owners converted it to a floor shifter. It works ok, sometimes I have to wiggle it into 2nd, but the biggest issue is that the shift pattern is backwards.
r is right and down, 1st is right and up, 2nd is left and down, 3rd is left and up..
Not like any manual I have driven and sooner or later I'm going to end up throwing it into 1st instead of 3rd...
Anyone have any suggestions on how to correct this matter?
Thanks for any assistance.