TH350 Question if anyone knows

[1977K10]

Last week my TH350 3-sp transmission gave indication that the forward gears gave out, but I still have reverse, I am wondering if its just the torque converter that has problems. I am going to be taking out my tranny this week to repair it, even if it means to get one from the junkyard and a rebuild kit from LMC in order to tear it down and rebuild it to like new. Any ideas would be great before I call the transmission shop, and have them rebuilt the parts I send them.

Thanks Shawn