Anyone ever run Speedmaster Heads on their small blocks

Bigger/ better than a stock J head.

Stock J head: ................. Speedmaster as cast:
.100 62/47 .................... 64/49
.200 112/99 ..................... 120/97
.300 157/128 .................... 176/134
.400 193/137 ..................... 221/153
.500 200/140 .................... 240/164
.600 201/141 .................... 250/168
I have 596 heads now with a little work done to them.. this looks like it would be a good Improvement for me...