That BCW short box is a game changer, but careful with the clear lids long term. They can get brittle and crack if you stack them heavy. I learned that the hard way. I started the same way, upgrading my most loved runs first. For me, it was the books I actually pull out to read that got the good boxes. The stuff that just sits in storage can wait in the old cardboard. It makes the upgrade feel worth it every time you open the closet.

My buddy Mark had a Pentax K1000 with the same gritty lever problem. He used a drop of 91% isopropyl on the pivot, just like you said, and it freed up right away. That was over a year ago and he's shot maybe twenty rolls since with no issues. It seems like a solid fix for old grease that's just gummed up, not for actual broken parts. I'd be careful with anything plastic though, the alcohol could cloud it.