Thinking out loud here
If to far gone to restore means to re chrome, one could always consider to clean them up as good as possible
It is ( almost ) always possible to get some kind of metal shine with brushes solvents rags.
and / or paint them with some heat resistant paint
It might not be the final exhibition top solution. But it will be original and possible to ride.
Often it does not look that bad either. One can always fresh it up now and then
Original pipes in good condition perhaps are not possible to buy Or very expensive I would
Guess US $ 500 to $ 1000.
That is a situation of personal preferences. And economy
Personally i most often prefer original even if some defects as long as it is usable -- than buying new non NOS.
We are talking a 50 year old Motorcycle . Enthusiasts understands that compromises can be necessary.