What a rare find and so cool they tested it. After 44 years, I'd assume the cylinder walls were probably far from perfect. However, in a recent Nascar dyno test I watched on youtube, where the engine sat for nearly 20 years and was full of surface rust on the cylinders and even pitting, it didn't hurt the power much at all.
It also appears the power was still climbing when they shut the pull down. Not sure why they didn't take it to 6500.
I know the article talks about the tunnel ram being good for peak power but reducing peak torque. I do not agree. Hot Rod, Engine Masters, Westech all have tested tunnel rams before, and they all seem to make more power everywhere. This does exclude the sheet metal intakes. I wouldn't be surprised if this tunnel ram was worth a good 30 hp and 15 ft-lbs over the stock LS7 intake.