|A matching set of OE valves should do fine.
Seals: OE or viton both work. V lasts longer, its an upgrade of sorts.
Guides: The machinist should be the one to determine if they are needed. They don't normally require replacing as a set (if at all) so stick with oe for consistency.
Before the guides go usually the valve seats need work. This can be were machine work gets expensive for a head filled with individual valves. Again, normally these are good and only require touch up but it the machinist needs to replace several it may be cheaper just to find another head.
I suggest that you out pickup a set of springs also. These do wear and are critical to a stable valvetrain.
If you need a full set of valves and your guides and seats are well worn you can make a case for aftermarket valves.
Some valves come with slightly wider stems which allows retention of oversized oe guides. The same could hold true for the valve seats but I'm not sure about that.
Ask the machinist about valve lapping - mine always chuckles at this one. Verify that they will polish the cam towers, this should be standard.
The last set I had done did not require seats or guides but they did get os ss valves and jwt springs. Shop charges came to $600.