I have a 1997 and a 2001 KX250 and those jugs to cross over.
Yes, the 97-01 cylinders do interchange as long as you use the exhaust valve from the corresponding cylinder.
In other words, you can't use the 97 exhaust valve in the 98-01 cylinder but you can put the 97 cylinder and exhaust valves on a 01 bottom end, ect.
Each year of cylinder used specific exhaust valves the exception being 98-99 used slightly different valves but they will interchange.
The 93 is just a bit to old to easily make work.
