I have Raiden looking perfect like this:
Line5x mode 320×240 optim.
Sampling phase 202 deg
H. samplerate 384
H. backporch 24
v. backporch 8
I stumbled upon that samplerate accidentally. I think this means the dotclk is 6Mhz:
6000000 / ( 258 × 60.49 ) = 384.457
But how could that dotclk have been calculated from the MAME sources?