Light metallic tapping and knocking

I bought a golf mk1 clipper with 158k on the clock as a project. Now there is a slight metallic knocking and tapping coming from the engine… I recon its probably valves and worn piston rings

Going to do a pressure test on the engine tomorrow and see what the figures are. I am thinking about a top end rebuild,

a) to get my hands dirty and learn something
b) I have a leaky manifold so may as well kill 2 birds.
c) I need to renew the cam belt so may as well kill 3 birds
d) Hopefully this will allow me to see if theres anything else that needs doing

I'd like to know:

a) What you guys think of the idea
b) Recommend anything else to replace
c) the best place to source all the parts / gaskets etc
d) Any hints and tips

Look forward to your replies