Have you checked that the upper cam timing marks line up when at TDC?
Mine were way out due to the PO having the heads resurfaced at some point. I installed some offset keys to cure that problem. I actually chose offset keys to give me 1-2' more cam advance to make things more peppy.
Are you sure the rattle isn't lifter noise? I get that most times after the car has been sitting for more than a few hours. Disappears as soon as the oil gauge is pegged. I too have new guides, chain and a new tensioner.

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Ben

'85 500 SEL
'85 928S2
'88 560 SEC
'90 750i