Just for informational fun, here is some information that I captured from Barney Navarro in the early 2000's - specifically related to pop-ups and his then experimental "High-Dome" heads.
He and I spent some time discussing the traditional flathead performance heads and I talked about the Harley KR and recommended that Barney incorporate some of the characteristics of the Harley KR into his cylinder heads. My next-door neighbor was super knowledgeable about KRs - had at least 6 of them in his garage and had built many for racing --> Daytona, Flat Track, Side-Hacks, etc.. His name was "Snuffy" Smith - he was like a second father to me and was a super intelligent mechanical wizard (in many things). My knowledge (and jugs, heads, etc) - came from Snuffy.
Another guy I know - Tom G. - helped Barney for a bit (said he was going to build a Bonneville car). Barney was happy for the help but had a falling out with Tom once he saw what Tom was up too. I knew Tom back in the day as well - he seemed like a decent dude at the time (was a shame that he wasn't on the up and up with Barney). Anyway, you'll find this to be an interesting read - glad that I captured it many moons ago!
This article was prior to H&H working out a deal with Barney to buy the rights, patterns and associated stuff from Barney. That happened relatively shortly after I penned this article.
Enjoy:
Navarro High-Dome Heads - DHays2022.pdf