HBTim wrote on 07/15/15 at 14:19:31:engine motor number is : P401112153
That's probably an '86
I thought those cut outs in the fin supports looked odd.
Yup you'll want to swap the rotor if you use that engine.
Swapping the heads would be ok if the bottom end is still good.
There's a lot we don't know about '86's which is the 1st year of production, we haven't seen a whole lot of them.
I'd check every part number between the 2 years you plan on swapping for revisions.
The format is xxxxx-24B00 and a revision to that will be xxxxx-24B01
24B means it's designed for our bike