a few questions on my first street truck

[dragtruck]

I've built drag trucks before, but never a street truck. I have a few questions and from what I've read in these forums, you guys have all of the answers!!! I have a 1972 GMC 1/2 ton long bed with a 307 and 3 speed manual trans. I haven't checked the rear gear ratio yet, but it is an open rear end. This will be drinen to cruise ins, not a daily driver.
1) I have access to a turbo 350 and a 700R4 auto. Which is the best choice?

2) What is the easiest way to convert from manual brakes to power brakes? I was told that I could get a brake booster and master cylender from a newer chevy truck and it will bolt right up. Is this true and if so, what year truck do I get the parts from?

3)I want to drop the rear 3"-4". What's the easiest way? My truck has leaf springs, not coils in the rear. I thought that all 1/2 tons from '67 thru '72 had coils, but the seller said leaf springs were an option in '72. Not sure if this is true, but I was thinking about putting the rear axle on top of the springs instead of under them. Is this a good idea?

4)Will a newer model split bench seat with a fold down arm rest bolt in my cab? A friend told me my cab wasn't as wide as newer trucks. If it will fit, what's the best year to look for? The gas tank will not be in the way because it's been moved to the frame.

5)Can I put 3 pt. seat belts from a newer truck in my truck? Since no air bags, I want to make it a little safer.

This is a great site with tons of info and thanks for your help.I look forward to asking more questions in the future.