727 transmision problem

I have a 67 Barracuda with a 360 and a 727 trans. I pulled the trans out and took out a 11' B+M converter and put in a 10 " converter that came out of my drag car a few years back. The 10' converter worked fine in the drag car and stalled around 3500. I believe I was told it was a Dynamic converter when I bought the drag car. I put the trans back in and ran the car on jack stands, shifted it through the gears, topped off fluid etc. The car sat for a couple weeks. Last night I needed to move the car to my other garage so I let the car off the jack stands and fired it up. The car will barely move forward or in reverse. I had to rev it to about 3500 before the car would even try to move and then it would barely move. It's like the trans is just slipping really bad. I did nothing to the trans other than remove it - swap converter and reinstall. The only thing I can think of is there was a lot of space between the flex plate and the 10" converter I installed. I had read years ago in a paper that came with a B$M flex plate there should be no more than 3/16 inch between the flex plate and converter when the converter is pushed fully back towards the trans and if there was more space to use washers as shims. I did use washers as shims to take up some of the space so the converter did not pull too far out of the trans when I bolted it up. Any ideas on what could be causing this problem? I think all 727 trans use the same spline converter except the early push putton transmissions . Is it possible the front pump just took a dump? Is the converter stilled pulled too far away from the front pump even though I shimmed it? Is the trans junk now that I tried to move it? Any help will be appreciated. thanks