Flatheads RULE! Years ago we were building a 40 ULH for Bonneville. I was working with a local builder
for some of the finer engineering. I set up a VL frame and tanks
with a ratchet top 4 speed a 45 springer to set it a bit lower, and custom built a set of Sportster 18" alloy rims onto FL hubs. PM discs, and built custom bars. We bored a couple of 74" U cylinders, lightened the flywheels, installed Carillo rods, and were having Lienwebber grind some custom cams when he got sick. After several months passed with him too sick to build the cams the money
started to run low and other projects prevailed. Ultimately I put a stock UL engine
in that chassis and sold it.
Panheads have a soul. Anyone who says they are slow either hasn't owned one or didn't ride it right. My 53 was a rocket. Jocky shift and 12 over springer with 16" hooks in a straight leg frame.
And then there was my 79 FLH. Full bagger clocked at 148mph on radar
and had more. Shovels are fast but mine did tend to shed parts