Best lift kits for a 72

[19gmc72]

I have a 72 gmc 3/4ton 4x4 and i want some opinions on lift kits. Good brands? 4in or 6in? Rear blocks or springs. i do haul trailers, boat isnt heavy but haul 3 ton of hay once in a while and need overloads, can i put overlaods on rear springs or do i need blocks?. i wanna be able to fit 35 without rubbing, im not going to mud it hard at all, but i do go up in the hills alot to crawl around on trails and want to use it for hunting, etc. pictures of setups would be cool too.. thanks