Getting the 68 on the road

[rnemtp3]

Hey guys, I need some help getting my 68 SWB SideStep 307/th350 4:11 rears on the road. The truck has been in the family for the past 25 years. Most recently it had been used as a work truck for my dad but has sit for the past 4 years. We are getting it back on the road. My problem right now is the brakes.
It has 4 wheel manual drums. I do plan at some point going with front disc but for now drums will have to do. I feel good replacing the wheel cylinders, springs, etc but my problem is the lines and hoses. They have leaks everywhere and the master doesn't look good either.

So here are my questions. 1. When ordering brake lines can I go ahead and get lines for power brakes now and use a new manual master? what is the difference in the manual lines and power lines anyway? 2. If I get a booster and a new master cylinder now with the drums, can I use them later for the disc. I know that I will have to add the prop valve. 3. Does the hose size matter in relation to the line size?

Thanks guys. I am sure that I will have many more questions before its over, as this is just the beginning.