The 2.5 TDI cylinder head nightmare

[A6C5V6TDi]

I own the BFC engine and things are starting to become noisy. Suspecting some rocker arms, hydraulic lifters, camshafts are worn out.
Now, the BFC is the B generation of the engine with 163 hp, but it supposedly has the same camshaft/arms/lifters as the terrible A generation.
The B generation supposedly has some things fixed, but they introduced the hollow camshafts, which can snap just like that.

1) Can I use camshaft/arm/lifters from any A generation donor engine?
2) Can I use complete cylinder head with camshaft/lifters/arms from a B generation? In that case will this new cylinder head run 100% compatible with the old one or I will need to modify something?

Please shed some lights upon the matter.

[A6C5V6TDi]

Nobody? The sound of the engine is becoming worse by month. I can't believe that just 30.000km ago, the engine ran like cat. Now 3 years down the road, after doing the complete belt change and reconditioned fuel pump, the engine sounds poor. Knocking and ticking sounds all over the place. The engine performance is still intact for the time being, the fuel economy is still ok too.

I am just afraid that when I open the engine covers I am not going to like what I see. Some rocker arms will probably be missing, lifters worn out. I don't know if its better to replace the broken parts or just use another cylinder head from a donor engine. I don't know if/which the cylinder heads will be 100% compatible with my BFC engine.