how do i put zz572/720r big block in a mid 90's ford ranger?

The 720r is the drag racing version of the ZZ572 and is therefore, not street legal. Unless you plan to drag race the ranger only, this is not the motor for you. It requires 100+ octane racing fuel to avoid detonation. And these days, that kind of fuel is EXPENSIVE, however apparently E85 is a reputable substitute. You would need to go with the lower end 620hp 572 because that IS street legal and overall better to put gas in for regular driving. As for transmissions, if you are looking for an automatic, the 2speed powerglide, TH400 or the 200R4 are a couple of worthy units. If manual, a T-56 6-speed from Richmond Gear could be a possibility.