You'll likely have plenty of vacuum and torque won't be an issue with the big inch engine and reasonable cam.
Every time I have run a single plane on an FE I have been happier than the same engine with a dual plane. This includes mild 390s through my 489 which is relatively similar to the build you are describing and on that one, my ported Victor was better everywhere than the ported RPM. I am not sure how they ported yours, but unless they ruined it by bad porting, I would expect that it will be a significant improvement over any single carb intake and certainly out power an RPM on a 470 inch motor.
Jay's book should give you an example that gets you close, but I'd say you will be just fine
- 70 Fastback Mustang, 489 cid FE, Victor, SEFI, TKO-600 5 speed, 4.11 9 inch.
- 71 F100 shortbed 4x4, 445 cid FE, headers, RPM intake, 1000 HP series Holley, 4 speed