Camshafts are the key to good performance - when they wear or become damaged on the operating surface performance will drop off alarmingly.
Regrinding or replacement is the only cure. Regrinding can leave a soft surface which will have a relatively short life span. A new replacement is the best policy.
Replace the cam followers and/or valve rockers at the same time - interfacing old worn parts with new is never going to be a good solution. Order ALL the gaskets and seals required at the same time.