I am happy to report that my new Epropulsion Spirit XS dropped right into my wooden Bayraider 20 with updated transom and fitted like a glove. No modifications necessary, so I consider myself a very lucky man.
The tiller has better clearance than with my old outboard, and if I get really fussy about weight distribution I could take the battery off, add the extension cable, and put the battery in a locker. Although frankly, having got rid of the weight of the old 6hp outboard, the fuel tank and a couple of small top up tanks, I am delighted by the new locker space now available to me for longer camping trips.
I may get around to the conversion of the three bladed prop I bought in anticipation of the problems of with the two bladed pro coming up through the lamellae, but the two bladed seems very manageable so far in my situation.
Going sailing tomorrow on Start Bay, and if I have to motor home up the River Dart, it will be so much quieter!
Thanks for all the shared information that lead to this decision.
Mark, "Pippin"