Yeah, column or 4-speed shifter. Usually it's a wide rubber band deal.
Pretty much any momentary switch would work, but the ergonomics with your setup are a challenge. I'd want a button on the top or something like a trigger at the front, so you can change gears and keep the button pressed simultaneously. Or, mount a button on the left steering wheel spoke like a trans-brake button; but the thing with that is the cord, which you might not want to look at. Using the horn button or ring is another choice, but it's mean another horn button somewhere and some cleverness with the wiring.
It's been forever since I used a shifter like yours, but hopefully routing the cord through the opening for the lever isn't a problem. Obviously it has to clear the mechanism and have enough free length for the Park - 1st range of movement.