I had an inquiry about 2 Stealths I have for sale and was concerned about the person using them with 318 heads. But I was surprised at the port openings when I measured them: 1" x 1 15/16"
I believe the LD340 has the port layout reversed...if you know what I mean.
Never had them side-by-side, but I was always under the impression that the Weiand Stealth and Action Plus were the same casting but with different carb pads.
The Edelbrock RPM and RPM Air-Gap are the same, except for the "air-gap".
Another bit of info that would be interesting is the actual internal cc volume of the respective intakes. However, just like ports in a cylinder head, more volume may not be as beneficial as port shape.
I ran the Stealth on my car for a season or two. But in the end, the Holley Strip Dominator was faster for my combo. The Stealth did actually flash the converter at least 100 rpm higher on launch. (I have an Autometer playback tach & swapped intakes during a weekend race.) But I didn't need the extra bottom end since I use 4.86 gears, 30" tall tires, 2.71 low gear 904, converter flashes to 5100+ and I shift at 6,500+