The link does not work for me, btw. But that is the correct PN.
Manifold heights:
RPM air gap = 5.7"
Performer RPM=4.8"
Performer =4.12
Super Victor= 6.25"
Weiand Stealth = 5.06" (sort of like the RPM in design but a hell of a tilt on the the carb base 4.37"F & 5.06"R and will probably jack the rear of air cleaner another inch.)
China copies of the RPM and RPM Air gap:
Assault racing
Search Results :: Assault Racing Products
Professional Products
Small Block Ford - Intake Manifolds
Speedmaster (aka Procomp Electronics)
https://speedmaster79.com/air-fuel-d...5-8l-351-12180
Don't get me wrong the copies are fine @ 1/2 the price of Edelbrock. I've used other Speedmaster components before with no issues.