The Suzuki Bandit 1200 head is basically the same casting as a 1990 GSX-R 1100. This means that the same tuning parts and techniques apply to both engines. You can also replace the Bandit head with a gsxr one without any trouble at all. Some tuners have also replaced the Bandit 1200 head with a gsxr 750 1988-1989 head. This head has smaller combustion chamber and brings up the compression ratio quite a bit. It is also said to have better ports than the bandit casting.
I had seen many gsxr heads before the Bandit project so I was a bit disappointed when I first disassembled the Bandit head. The casting appeared to be lower quality than the gixxer heads I have seen. The ports do not match well to the intake boots and seats did not match to the ports. The cast had some core shift also.
The ports are big enough already so I just smoothened the casting flaws and core shift. I matched the ports carefully to the intake boots and. I also matched the valve seats to the ports the best I could considering the low quality casting. I used a 40000rpm pneumatic die grinder for the job.
I also milled 1mm of the head gasket sealing surface to raise the compression ratio from the original 9.5:1. This 1mm still left 2,2mm valve to piston clearance with the gsxr 750 intake and stock Bandit exhaust cam phased at 103/104.