HRD, I had that EXACT problem when I went to put the CAT V8 in my deuce. I think the multifuel may be a #1 but it's not a true one because there is one or two bolt holes moved from true SAE patterns. Like around the recess for the winch drive shaft, etc. I found the dimensions online for the SAE patterns and drew them out on AutoCAD, the #1, #2 of the CAT, and #3 of the trans bell. I had a buddy print them out on a large plotter at 1:1 scale then overlayed that sheet onto the factory aluminum adapter between the multifuel and the trans bell. I aligned the larger patterns, then center punched the middle pattern that I needed for the CAT, then drilled them out.
I then took it to another buddy that had some big machines and had him mill off the step on the adapter plate so it would mate flat with the CAT. This is how I got them to bolt together. Oh, the patterns are pretty close together when just going from one to the next without skipping a number so I had to grind small reliefs into the trans bell then use Allen head bolts to bolt the adapter plate to the CAT after it had been bolted to the trans bell. I'll grab a picture today. The multifuel's large pattern is still visible on the plate.