I did what you are planing, but took a bit of detour and blew right through the budget badly with some serious mission creep.
A little later I harvested the 950's gears for the installed SD engine;
My advice reading your thread;
An impact wrench and the right sized sockets gets you everywhere you need to go in an engine rebuild, except for the valve stem seals - need a special clamp for them.
if the shifting is buttery smooth and no false neutrals then leave the bottom end and don't split the cases.
But it is not so much more effort to do it, especially if you buy a complete gasket kit from Athena. (I used one 2 weeks ago, it is brilliant). I would as a matter of course change; the 3 shift fork rollers, cam chains, any notchy bearings (all are standard size and good bearing shops will have them), and have a good look at the shift drum - from 2005 they upgraded the drum to prevent a fairly rare issue of one of the walls close to 6th gear position breaking.
My experience with my motors is that all the hardwear in the motor is practically bullet proof and very hard wearing. My 950 engine that had been beaten on for 70k km's looked practically pristine inside.
Your oil leak if it is from the base of the rear, is almost assuredly the Pydon effect. If budget doesn't cover a new bottom end then I've seen an engine repaired by using a new gasket with a thin film of gasket sealant on both sides and then torqued to spec and a second time after a few thousand k's.
Good luck, shout if you need help.