No, unfortunately I don't have a paper pattern, (typically flew by seat of pants) I would have drawn that on a flat square plate, drilled the holes to match to the tractor frame, I then would have left that plate on the tractor frame and over top the plate, stuck my motor onto is,, I would have positioned the motor, clutch end, centered to where a v belt would in theory come down to say mount a mower,, once centered to that, squared to tractor frame, I marked the motor mount holes. Now, having 8 holes in that square plate, I just shaped the plate in the above picture, making it kind of pretty,, I subsequently, elongated the 4 motor mount holes, so I could slide the motor further back by roughly 3/8 inch,,
The motor adapter plate is easy to do, the more difficult part is to match to a decent exhaust. What I did start with was,, I did have an old 646 OEM muffler. From there, I ended up purchasing 2 pipes off a 6018? and a tiny bit smaller 3 ft strait OD pipe, (bought new, from online source, I needed this to join the 4 pieces of pipes together,, )(3" piece of smaller OD pipe, inside 2 pieces of pipes,) welded it all up together and called it done.
Above, I mentioned is 3/8 plate, it was a 1/4" plate.
Have a browse through this thread,, in there, you can see my trials and tribulations,,,
Just skip to the parts of motor and pipes,, and whatever else you might prefer,, Exhaust, honestly turned out OEM looking, and not as much as a challenge as I originally thought. You have a pump mount? if not, you can see how I did mine,,
Well, I really,, really didn't have much of a choice.