I like what you did, skrews, with smart porting on factory castings that most don't even realize have a lot of potential. Good job.
Here's a pic off my phone of my 915 j heads, I left the guides, just narrowed them a lot and raised the roof quite a bit, 186cc measured. They flow over 270cfm after final touch ups and
[email protected],
[email protected],
[email protected], and 250 by .400 lift! The chambers are 60' cc in this pic.