New to lowering truck.

[coater]

I have decided to do 5/7 drop on my 85. Could someone tell me what is needed to accomplish this.
I assume the front would be 3" drop spindal w/2" drop spring. The rear is what I have some concern about. What is the best way to get the 7" drop in the rear.
What would be the best shocks to buy. I would like to get some very good shocks all the way around. I tow a 18' boat once and a while and would like to be able to raise the rear alittle to be able to tow my boat. I'm going to use 20" wheels on it,so I'm not sure if the rear would scrub while towing my boat. Could you use air bags just for the rear to air up and down?
If anyone knows where I could go to read up on doing this would be great.

Thanks for the help.