Which if I'm reading you right really isn't all that terrible. What it does have is a broad torque curve and hits 500 lbs./ft at almost 5,000 rpm, should be good for something.
Looking at the 2 HP/C.I. target efficiency number posted originally, I'm not sure where to find a 15-20% increase in power but I don't think there's much to find in the cylinder heads? Perhaps a "better" intake might net 20-25 hp? Larger headers would help for sure and a roller cam. The heads are not race heads by any stretch, more like super-prepped factory replacements.
At the time, the heads were chosen based on budget constraints and ease of install because they worked with what I had on hand. The flat tappet cam was chosen for the same reasons and was spec'd by they shop that did the heads based on intended use. But just because the parts didn't cost a fortune didn't make the results any less disappointing.
Maybe I will look into re-testing after it's been checked. They dyno shop that I originally wanted to use was flooded out during Hurricane Sandy and was still not in operation at the time I tested the motor in 2016. Heard they are back up and running it again, might be worth a call.
