Kent fuel pump spacer thickness variances - Tracking down tappet type noise.

Hi All,
 
Is there a major issue using a different thickness fuel pump spacer. A 1300 I have has a spacer twice as thick as that on a 1600 I have and the 1600 has quite a tappety sounding rear (as in near back of head/motor). My hearing a bit crap so can't pin point it.
 
I have adjusted tappets to book spec but still quite noisey. They only thing other than non std tappet specs I was thinking was that fuel pump lever is riding the cam lobe in wrong spot possibly due to incorrect gasket thickness?
 
Any opinions on this?
 
Alternatively what cam did Formula Fords run? Was is not "GT" spec meaning a bees willy more agressive than std? So my clearances should be ok as I have set them if not I am can re-adjust.
 
Thanks,
Rhys