Motor and Tran not lining up easily

Hello,
My son and I are in the process of adding a motor to our 68 Valiant(Slant6).
We are having issues trying to get the motor back lined up on the tranny(which we didn't remove from the car. only the old tired motor). Since the vehicle is on an incline on the driveway, I am thinking that maybe the tranny slipped back while being disconnected from the motor? May be gravity made it slip back on us?
If so, How can I get it back to line it up with the motor? We are about 1/2 inch away from getting it to line up to be able to put the bolts in the tranny from the block.

Help is appreciated.


I have had some trouble in the past with the trans being too far forward. Loosened the trans mount bolts and there is some play there. Could be your issue.