Whats the pump at?
Anything over 17 deg ATDC means smoke, noise and rougher idle.
I'd check that cam gear as well, I know the 602 engine (5 lung turbo) has a bulliten about the chains stretching. We had one a few days back that was at 24 deg ATDC on the pump yet the can was at 2. That one needed cam and crank gears but, the pump timer was ok. And yes, you can replace the long guide with the head on and lower cover off, cut the guide near the pin and remove the pin with a stud extractor and a snall pry bar. Then place the long guide/rail in and pond the pin back in.
The things I replace with a 602/603 chain are tensioner, cam gear, chain and upper l/h guide.
Project Smoker, '87 603 powered wagon
Hauler, 96 CTD can you say torque?
Toy 73 Cougar xr7 convertible
Acme Automotive Inc.