Yes, based on the video that Fabian posted where he said that the HT slant head is a high compression head compared to the other HT heads and most of the after-market billet heads that he has tried. I will buy a compression tester of course, and use it before doing anything to modify the head.. no point in omitting that step when compression testers are only £15 on Amazon.
I was only asking about whether the head will break if it is reshaped a bit, and whether some reshaping would help with such a weird shaped combustion chamber.