I can't remember if you have the 250 or 350. I'd say based on that answer would dictate whether or not to get the blocks. The 250 is pretty close to level from what I recall so you'd definitely want the blocks if you're going up in the front (otherwise you'll be nose high).
I believe the 350's come with a 4" block, so with a 2"-2.5" leveling kit, you'll be pretty close to level. Might be worth measuring your stock block, then go from there. I went with a 2.5" Stage 2 ReadyLift kit on mine (no block change on my 350) and it's pretty close.
Late reply have not been on in a while . I have the 5 inch block . Slightly higher with no trailer . . Im not a fan of level or nose high. Yes it has the shim for driveshaft Not sure about the 4 inch id say its like stock. . I like the idea of being slightly higher than the majority and looking stiock.