Hi and welcome to the world of the orphan/fridge trucks. I'm thinking if you cap the top of the master cyl with saran wrap or some way to make it airtight you shouldnt have to bleed the brakes. Even just doing it fast should be ok, as long as it doesn't run out to the point below the output line. I have run multigrade in all my old trucks for 40 years with no ill results. Since most of my trucks are diesel these days, I run delo 15-40 in everything, including the gassers. The tranny and rear end use plain old 90 w, but often all I can get is 85-90 and I assume thats the modern equivilent. I don't think those gears are too fussy as long as they are at the proper level. Never worked on a diff without a cover. Seen 'em, but that would be ok with a full floater( like on a 3/4 ton plus) because you don't have clips to pull for axle shaft removal. I guess you need the factory service manual to figure that one out..... Ebay is the place. Havent looked into power brakes, I just maintain them really well and stand on them. I live on a 75 sq mile island with about 4000 people and no traffic, so I plan ahead. Hope I've helped some. It's been a fun learning process with old ford trucks and has been a lifetime of enjoyment for me, having bought a '28 model AA 1 1/2 ton at age 19, 40 years ago this summer.