When buying an engine what else do you need to get to complete it? Thanks for the help

You'd generally go for a few extra Glow Plugs suited to that engine, a flywheel, clutch, clutch bell ( If necessary ), clutch bearings ( If necessary), a pipe ( Again if needed ), a header ( if needed ), and you may need engine mounts.

Pretty sure that should set you good..

really only plugs, pipe\header for increased perfomance, and clutch bearings. You can never change your clutch bearings too often.