rear brake upgrade on 70 dart

hey guys.... i just picked up this 70 swinger and am back in the mopar thing..... i have previously owned (in order) 67 polara 4-door, 66 coroonet 500 with a built 440 transplant, 68 cuda conv. with a 71 340 transplant. I'm just playing around with this thing and plan to keep it stock. It's originally blue/blue with 225/6 a/c, ps, pdb. I think the body is pretty sound though it has a pretty crappy brown paint job now and the interior is major ugly. It runs good, has a rebuilt carb, distributor, new battery, some front end parts replaced, alignment, major tune up, new cragar rims, good tires, etc. I know it's not fast like most of your cars but I love the old beast and I'm sure I got you beat on MPG! The first issuses: 1) hard to start. replaed coil, problem solved. 2) Trans leak, mostly when sitting - tightened pan and I think i got most of it. 3) Brakes don't work well - booster checks out, bad seal on one rear so rears will be done. Fronts (disk) look good by eye. I drove it home for $1000

Here are my questions. If you can help I would greatly appreciate it.

1) are there any cheap, junk yard upgrades for the rears with the 7.25 rear end?
2) The drums are shot, any recomended suppliers for good internet prices on drums, w/s kits, seals, shoes?
3) the brakes worked but felt like manual brakes. I vacume tested the master and it is fine. Do you think it is just becuse of the rears or is there a possibility that the front calipers have issues.
4) lastly, is there and EASY upgrade for the fronts to bigger disks........ thanks.... i'm hoping to get this thing stopping the best it cann but not spend too much.....
5) I don't see any proportioning valve - and I heard mention of a check ball for the power brakes, where is that and how can I check it..... no pun.

Also, looking for a/c controls, original front seat, front valance, radio/heater control bezel... thanks...

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