727 no 3rd wont shift
Dude, just run it on jackstands!! Be forewarned though, you'll think it's not making the 1/2 shift because it's freewheeling in 1st, you won't feel it on jackstands. Just hit 3rd (used to be 1st) and the wheel speed should pick up.
I've done a few of those conversions but the transfer plate is no longer available. It was spelled out in the old Direct Connection race manuals.