T-5 swap woes

[Ultrasummer]

I have a 1968 short bed stepside. When the old 307 went, I put in a new crate 350 and a T-5 trans. The T-5 was said to be WC, the front part was out of a Camaro and the tail was from an S10. When it fired up for the first time I was so pumped. Music to my ears. When my mechanic friend told me to go ahead and put it in gear just to see if it rolls, it kept popping out of first. He looked everything over and later pulled the trans and opened it up. He said it all looks fine except 1st gear is noticeably worn. I mean ....bad. So now the search is on and everywhere we've looked, nobody has this first gear. Or those who say they have it online don't answer after waiting for the part for weeks. Anyone have any suggestions? Now I will say this, my mechanic friend has been doing the legwork of trying to track one down so I don't know who he's tried and who he hasn't. Seems we've come to a roadblock with the project.