Outboard question

I've been thru the ignition on these things albeit 10 years ago, neither has seen water since. If things play out I may need 2x the parts for the fleetwin.
I have a line on my dad's which is a twin to mine.

On the 63 18hp I have never been able to pull that thing over with the pull start, even in the 80s when I was 18-20 yo and the strongest I ever have been.
Now in mid to late 50s, bad shoulder, no way I'm pull starting that thing.

. I have to use the electric one. But it has always cranked up easily with barely touching the starter button.
I once had an early 80s 25hp Johnson that I could pull start easier.
Nother thing on the '63
Ever since Dad got that one in the 80s with a cracked skeg, I have not been able to stop that thing from taking on water in the gear case. Different skegs, new seals more than once, I think if I get that one going u am gonna look for a whole nother lower unit, I think there's an issue with matching machine work between lower gearcase and skeg. Kinda like mixing rod caps on a different block on a car engine sort of thing...

Any tricks? I've had skegs off and lower units apart on other engines over the years without issue but "this one" has always been a problem.
Because of that it has been used quite minimally and I know it's been 15+ years since it's been out of the shed
What years and hp models would interchange with that engine for a while different lower unit?