The glow plugs are also different lengths depending on inclined injection or not.

Recommend you keep the new lifters with the new head, and you should mark each lifter to ensure it goes back onto the same valve. If you can't do that, then you should bleed down each lifter prior to installing. There is a small hole on the side of each lifter in the oil groove: point that down, then pump the inside assembly with your thumbs to force the oil out of the hole. If you don't do this, and the new lifter has too much oil (because the valve stems are at different heights because the valves wear into the valve seats), then the lifter will hold that valve open and that cylinder will never develop compression until the oil pressure in the lifter bleeds down. I'm sure you can guess how I know this...

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC