Well I suggest you buy a new a new set of shocks, to relly learn how to build them. If you are doing some jumping (mild). I would go with a medium viscosity like 40-60. But if you have alot of aluminum parts on your truck, and its heavy I would go with a higher viscosity. If you are going to rebuild your own shocks, make sure to get new o-rings, and make sure to put them back together just the way that the instructions state. I have a set of progressive suspension shocks, with the piggyback reservoir. They leaked so bad at first. When I got the new RC Raven and Shocksocks I rebuilt them again, which was about a month or so later. Anyway when we talk about springs, I like the dual rate springs. At slow speeds they are stiff, and then at a higher speed they really soak up the bumps. It's up to you on which brand you decide. Do your homework, and ask your friends. If all else fails, post another thread on which ones to buy for your RC.
Just my .02
Woody