I believe Hughes has the intake manifold flange heights listed in their manifold flow tech pages. They measure from the front China Rail.

Chip, with stock motor mounts, it seems wise to me to run some sort of a movement limiting chain, strap or something to protect the shaker from being smashed when the stock driver's side mount lets go. It's pretty much only a matter of time until a stock mount tears in half, even with a stock 440 motor.

1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)