That's what I use on the bottom for vent control with my current mini. I'm also guessing that there wouldn't be as much of a vent clogging issue with the three vents set up the way they are. The current SJS needs a can with holes at the top to prevent clogging. Setting up three vents with little handles might look strange too, but could work well. I emailed the guy with the three vented SJ, hopefully it's still available.
I suppose as old and collectable as your "Brownie" is, you wouldn't want to cook on that. Looks very nice, great find!!