I have not run an RPM Eddy but wanted to. Your finger pointing at the Holley Dominator as the possible culprit is logical but the cam you are running may not be happy with the rear ratio or stall of the torque converter etc. I just went through this over at FCBO as the designer of my engine is over there. My problem was after careful measurements it seemed the RPM intake with my stock dual snorkel air cleaner would not fit under the hood. The RPM eddy is 1.75 inches higher than the stock intake manifold. Some have problems and some don't. Some find out the hard way after installing it and try to close the hood for a test drive. 1978 NYB doesn't have a problem and runs a rather low profile air cleaner. My goal was/is to have my engine look stock. With this problem in mind I went to FCBO with the topic title "Holley Street Dominator on a RB stroker."
Since mine is not a stock sized 440 it is a different can of worms possibly. In the end most experts and Dwayne Porter of PRHeads [engine designer]on FBBO said in my case it would be no problem and barely noticable as the engine will be making more torque than I need down low on street tires. Many guys rave about the Holley Dominator there and with the low profile but very good flow. I have 3.23 rear also but had a 11 inch [hard to find and out of production I hear] converter built for my application. They wanted the weight ,tire diameter ,rear ratio, cam card, displacement and style of most driving. We don't know what cam you have and what you want from the car. You could possibly put a new Performer RPM for 300 bucks only and it may help a little or you could still have the same problem. What you want from the car first would be helpful.
I patterned my build from Furygt and MEV. Mev runs a 3.23 rear in a 66? 4 door New Yorker with a 440 stroker ,cast iron exhaust manifolds [not HP's} weighing in at a whopping 4700 pounds ,drives 50 miles to the track and is in the mid to low 12's. An old saying says "the torque converter is where the magic happens." Lot's of ways to skin a cat as they say.