I'm not going to say those numbers are weak, but...
Iron J's ported w/2.02 nail head 11/32
.100 78
.200 146
.300 215
.400 254
.500 278
.550 284
................
I would expect heads like these to blow a ported factory casting out of the water, I mean 30 cfm better out of the water.
I'm always reminded buying a flow bench was one of the best tools I've ever invested in with regards to building power and finding truth in advertisments.