Yeah, I have the flow numbers around here somewhere, but they were about as "good as it gets" for GT40's. Port size was a perfect match for the TFS-R:That would have been a fun car with 325whp , IRS rear end and suspension work. I have a lot of Maximum Motorsports parts and suspension work on my cobra.
You'll only go as far as your heads will take you. 290whp on ported gt40 h/c/i sounds right. The 11R heads come in a 53cc combustion chamber flavor to really bump up the compression on n/a builds. They feature completely revised valve angles more in line with LS heads. 380rwhp isn't out of the question even with only 302ci these days if you can match all of the components perfectly. However, with newer generation On3 Turbo kits starting @ $1800, its hard to drop big coin on NA builds assuming your starting with a 5.0. Boost is hard to beat.
Yes, I was the lone N/A guy in our group, LOL! Everyone was using a blower, save for my buddy who was big into nitrous. Everyone was mindful of the stock block limitations, so I think the highest anyone in our group got was 534RWHP. That was a set of AFR's with a Crane cam (2034 I think?) Performer RPM and an S-Trim.