All I can tell you is I use Hughes roller tip rockers in the 440/493 in my 63. I built the eng and installed it in the car in 2011. Its a mostly street car that I drive to the track about once or twice a year and race in the NSS class. Its almost 11 years on the eng and these rockers have been flawless. I adjust my valves once a year and most of the time they are still on the money or very close within .001 or .002 out at the most. Its not a high dollar race eng as its just a mild pump gas 493 and my cam is a flat tappet thats 264 & 270 @ .050 with .585 & .592 lift and a 110 LSA. But I love these Hughes rockers as they have held up great for 11 years so far with many street miles and a few passes a year in the 10.70 to 10.90 range. Ron
I decided to check clearance on the valve covers with each rocker. Hughes wins! I'm gonna run stock-looking valve covers and they teeter on the Harland Sharp rockers and sit flat with Hughes. I checked the fit with no gasket. The Harlands run into the baffle. If you're dead set on using Harland Sharp you could always grind off some of the rocker or cut a hole in the baffle. The gasket might give enough clearance as well. For me, I'll just run the Hughes rockers! Hughes also sent a bunch of shims and spacers with to get the set up right.
The geometry always depends on the cam. Change the lift and the geometry changes. Such is the nature of the fixed position of the rocker shaft. A rocker that has excellent geometry with a .500 lift cam will deteriorate with any increase or decrease in lift whereas another brand of rocker's "sweet spot" might be a .600 lift cam. Unlike ball-stud rocker systems, there is Mopar rocker that is ideal for a broad range of cams
My Hughes rockers are pretty much dead center on the valve head. As I said they have worked perfect for me for well over 10 years in my mild 493. My cam is a mild flat tappet of .585 & .592 lift but the Hughes have worked awesome for me and my combo. Ron