Thank you, this is what I needed to know. I thought that this swap may have been popular at one time to get the additional power. I have both starters so I will compare them. I expected to have to use the '41 flywheel and clutch. Actually, the hood and front clip were unbolted back in 1973 when I pulled the original motor. I intended to do the motor, clean up a few dents and paint the fenders back then but the car has been in the same dry storage for 45 years. I am going to need to move the car soon so I may move it into my shop as a winter project.
You are absolutely right about inspecting the motor. At the very least, I will pull the head, grind the valves and check the bearings etc. before I detail the motor for installation. It has been a lot of years but I still remember the Plymouth even with the small motor, being a delight to drive.
Fred