while the head is off, is the only time to replace the camshaft. so a full top-end rebuild may be in your future. the lifters on most 200's can only be taken out with the head removed. so this would be the opportune time to replace a worn-out cam; and the timing chain; especially keeping in mind that if your timing chain goes on a 200, so does your camshaft, as the bottom of the con-rods pass into the camshaft's space.
since the 200's head itself is being rebuilt: using ford 305 valve springs, hardened valve seats, opening up the valve passageways a little while you are in there (read: port/polish if you want), will all increase the longevity of the engine, and you have the choice of going with a mild-performance build, or completely back to stock.
my 200 was built in April 1982; just rolled over 75K miles, (it was a garaged car, and hadn't been drive at all since 1995) and I have been seriously looking at doing a new cam, and the double roller timing chain simply for increasing the life of the engine. however, once I pull the head to get the lifters out, there really isn't much of a reason to leave the head alone, or to not replace parts that would be made with stronger alloys than they were back then.
as I currently have a carb/vac issue with my engine, I have been looking into the cost of a top-end rebuild vs just replacing with stock, and the difference is nominal. a mild build to take my (rated) 99 hp engine to 120-130hp would cost about the same as leaving everything OEM, but I would be greatly improving longevity, and increasing the range of the power-band, and bring the engine into the range of acceptable performance for a mid-sized car of today's standards; and that's all before tearing into the bottom end.
Good luck with your project!
