Why would euro 500 cams not fit in it if it were a 116.964? I've heard of 4.5 cams being put into a 560 with just replacement of the hydraulic ball studs with mechanicals. And I know 3.5 cams work fine on a 4.5 - I've done it. I am pretyt sure they'd fit either way.

But wouldn't 420 cams already be more agressive than 500 ones, regardless of euro or not?