fran...k.
Husqvarna
AA Class
Heres the one from issue 16 Classic dirtbike. Apologies for poor scanning.
View attachment 22297
The origional post says shoe horn not splice. Often using the lower cradle and swingarm is the route decided upon. Not only the chain on the brake side but the lack of a top motor mount most of brand x has. All the air cooled large displacement stuff is long past it's design lifespan by now. How about something like the rotax 406 used by can am and atK? The air cooled top end will fit on the water cooled lower end with a swap of the cylinder bolts/studs. I missed a very nice six speed husky cr 500complete transmission, which is the same as an wr,xc 250 transmission(well equivelant years) getting distracted instead of bidding early on ebay lately. It went for barely over $50 plus shipping. The third gear (500xc, 430wr,others) was still availavle last I checked. Metal chips run through the whole thing? Some of the listings do have sufficient pictures to evaluate. You said transmission not starting primary gearing was the issue.