Just bought a Honda 8 HT with power tilt , electric start, & 12 amp output alternator for around $3,300 as a kicker for my new Hewescraft. Why pay for a rebuild on an old platform, just go new, dump Yammy & start over with a better product.
I also currently have a 1996 yammy 9.9 HT on my Lund Newport 2100 & it has worked well for the last 10 years, & is still going strong.
Good Luck, hope your downtime for this is limited.