If your AC is like mine, there is a passage that allows compressor boost into the actuator. The actuator has a hose barb and a bleed jet. When air is not allowed to pass through the hose barb (because it is capped or there is a hose attached with a closed switch on the end) boost is controlled by the orifice size of the bleed jet on the actuator. ("Low boost setting")
When a hose is connected to the barb, additional air can be bled off from the actuator. How much additional bleed may be determined by a second bleed jet in a switch connected to the end of the hose (ala original AC3 setup "Hi boost setting"), or by inserting a "plug" with a small hole in it into the end of the hose (sounds like what you did), or by attaching an adjustable valve to the end of the hose. But if using a valve like this, it should hold a constant orifice. You wouldn't want to use a spring loaded valve that is normally closed until a certain pressure is reached, such as with a conventional check ball boost controller.
In any case more bleed = more boost. A small change in orifice size makes a big difference in boost, so be cautious. Any of the ways above should work fine to control your boost. Like I said earlier, I capped the hose barb and change the jet on the actuator body myself.
BTW, one of the main reasons I did this was the toggle lever on my AC boost switch was rubbing the bottom of my hood, this resulted in crazy boost variations as the engine torqued under load. Something to keep an eye on.
Some ACs, such as P51's, have an external line carrying the boost signal to the actuator. With the external line, it can be cut and a conventional boost controller placed inline. These valves function by holding the pressure out of the actuator by way of a spring loaded ball. The user can adjust the spring tension. Sufficient boost overcomes the spring pressure and the signal reaches the actuator. The actuator then prevents boost from rising further. Not sure how the original AC actuator mounted bleed jet would factor in here. Hmmm... Anyhow P51 has (or had) his setup like this so he would know.
As far as using an electronic BC, I think you would be the first. I imagine it would be possible, just might require a fair amount of ingenuity if you lack the external signal line.