CSL Engine Rattle - Help

[nigelonich]

Had a look at some historic posts and Id appriciate some help>

Background> 2003 CSL with 65k miles bought with engine fault which resulted in fitting a 40k mile engine froma damaged CSL. Engine fitted and valve clearance service done at the same time but there were shims out which was a worry.
Current situation> valve clearances all good but engine sounds bad and mostly coming from around C5. Inspection shows damage to the cam and to the rocker but likely more damage on others.
Advice needed please>
1) I looked on you tube and there are some great videos of how to take the vaonos off and I wondered if I got a cam locking tool is it easy enough to replace the cams and rockers?
2) Do I need any extra special tools?
3) Already spent lots on this car and looking for the fit for purpose solution. So do i get a set of good used cams and new rockers from BMW or get a new set of Shrick and followers?
4) based on the above do I need a remap as I want to keep it right.
5) Anyone got the part i need?

Cheers in advance.
Nigel