Hi Max,
with the split machine, because it had gone to 21 inch and I didn't lengthen it, I moved the motor back 25mm, so it was able to have the 2 rear holes drilled in the existing base, then I welded in a piece of 50x3 flat across the front and drilled the front holes in that.
The Honda Victa had to be lifted up the same as any Briggs/ Techumesh motor has to because of the longer shaft, muffler was not the problem. I did use a Briggs ring, mainly just to fill the gap, got 2 holes to line up and notched the ring to allow the other 2 spacers to fit
