check that the lines are blocked off that are ment to be.

i removed all the EG shit off of my motor when i put a weber on. its not needed and does nothing. i made up a small plate to permanatly blocked off the exhaust gas recirculation too altho it was long blocked up with carbon and gunk.

if you ran it with low oil it could have started to wear something causing the noice. i used to run my 4ac low on oil all the time, it loved it, dry sump ftw. is your water pump leaking out of the little hole in the housing? could be that.

do you have the timing cover fitted? could be just the normal operation noise of a old timing belt and you only just noticed it.