I am looking at putting larger exhaust valves in my cylinder head and was wondering what oversize valves are available for the B207 cylinder head. In the States for the L61 you can get 1mm oversize but not certain if this is actually oversize or conversion difference from inch-mm

Why do you want to do this? If you want more power, go down the ECU reprogramming route and see what the engine can really deliver. Old school camshaft, porting and valve sizing mods don't make sense with these engines this century.
I did all that on 'atmo' engines, on a range of cars from Europe over the last 25 years. Then I discovered, recently, the power of the ECU controlled boosted turbo engines from SAAB.
Enough said.

I have a z22se engine and the saab b207 head is the same only sand cast rather than lost foam, the strength is a + point. I am just about to port it so as to allow more flow. I have a 1.3lt s/c bolted on and with cams will produce 360+ bhp but the restriction at the moment I feel are the exhaust valves asr a restriction so as wanted to try some larger ones. You can get 1mm oversize valves (so they say but could be inch to mm conversion) from the states. I am updating the ecu also as the final aim is about 400bhp assuming the linners don't give first