Christian,

if its a Dr. Jeckyll and not a Jeckyll, it was sized and designed for 120 4 bangers. I'd plan on a good 90 2 stroke of that's the way you want to go. A Webra 90 or an OS 95 long stroke might do nicely. The Jeckyll, on the other hand, was flown by Chip with a Webra 60 LS in '91. LS 60's are not hard to source including YS 60 AR's (pumped) or even OS Hanno's (quite a bit rarer). You might find an OS 61 RF a little more easily.

I'm glad you find Jett pricing reasonable - they are about the most expensive engines out there other than YS 4 strokes! Nice engines though.

What are the specs of your model (span, length).

David.