Very nice! It's always nice to see others using the HP-UHU. Please keep us posted on your progress with this!!
What do you have the current limit set to on the HP-UHU? Any signs of heating? Reason for the question is that as far as I can see the IXFH30N50 has 2.5 times higher RdsON than the IRFP264N so it should generate considerably more heat. Shouldn't be a problem if you supply adequate cooling though.
Don't worry about your english!