[T2] Valve seats

[Bob Perring]

Has anybody here had personal experience,
or know of a source for precision work -  for replacing valve seats 
in a type 1 head?
re:
1600 CC Dual Port,
Stock valve sizes,
Original head manufacturer = unknown (probably Brazil),
Current mileage estimate on heads = 30K.
1.
Can I do this myself with good results,
or should I ship the heads off to a reputable machine shop that does 
such work ?
2.
Where can I still buy quality product heads, if necessary ?

Thanx,
Bob Perring