Carter AFB/AVS carbs are designed to run up to 10 psi of fuel pressure. If you PM me your email address, I will email you the original Carter spec sheet for adjusting float level for the operating fuel pressure.
While there were some minor changes to the AFB/AVS design when Edel started making these carbs, there were no changes in the fuel delivery system. An Edel air horn with floats in place, placed next to a Carter airhorn will show a mirror image. So Edel carbs will operate with exactly the same fuel pressure as Carters.
The 5.5 psi quoted by Edel gives the datum jetting of the carb because fuel pressure affects fuel level, which affects rich/lean.