Iron? Factory? RHS? EQ?
MRL gave some good info on the valve seals.
However, you still need to do some measuring yourself or verify the measurements when you get the heads back from the machine shop. If you are trying to 'blueprint' the heads then naturally the goal is to have everything measure the same wherever possible. If it's just a basic rebuild, it's probably not that important.
Do you have a checking spring? What about a valve spring height micrometer? You may (or not) have to shim the springs to get the installed height you need. Probably should also check retainer to guide clearance once the machining is done.
