I highly suggest replacing the exhaust valves with stainless steel ones! These Suzuki carbon monsters are well known for burning exhaust valves from retarded timing.
I have rebuilt 5 G10 heads and I am doing my 3rd bottom end rebuild right now................
http://geometroforum.com/topic/638797/
http://geometroforum.com/topic/1299263/
http://geometroforum.com/topic/1144189/
http://geometroforum.com/topic/2175380/
Stainless steel valves are available here.............
3Tech Performance
I also suggest using the 3Tech head bolts!