What are the best brand of shocks for a '77 K30. I want to swap a cummins into it, and will need heavier shocks in the front. I will also need the stearing cylinder (I dont know its normal name). Whats the best heavy duty brand? I dont have the truck yet, but my buddy is selling it too me soon.  

If you are going to swap a Cummins into it, the shocks are your smallest problem. I would be more concerned about beefing up frame rails and front suspension for the 1100lb plus motor than the shocks. On the shocks themselves, you need to switch to a after market quad shock setup. Make sure you beef up and weld upper shack bracket on frame as they have been known to loosen up on rivets under severe usage. BTW, if I really wanted a oil burner in it, I would use a 6.5 as it would basically be a bolt in with some wiring and ECM control circuits.