67 valiant slant trans to 77 truck slant trans

It will physically bolt to the motor; however, the problem is the 77 torque converter. The nose of the converter is larger than the opening in the back of the crank. One solution (but expensive if you can even find a converter company to do it)) is to have a converter made with the earlier small snout nose and internally with the 77's spline count. You can't use a pre-68 converter as the spline count and nose size changed in 68.