To clarify on that shifter, we used it for many years as our standard cable shifter on Brazilian built cars and I only ever sold a couple of them as retro-fits. So there's several hundred out there, but only a few that are on earlier cars like yours.
The aluminum collar is your reverse lockout and that is all it does, it has a plain metal shaft underneath that could be changed with some fab work and keeping the cable attachment points the same. You'd have to fab a flip lever or some other sort of lockout for reverse if you got rid of it, but it is possible.
As for e-brake position, you'll see original cars with the brake on both the left and the right of the shifter. I prefer it on the right simply because whatever you put there is partially impeded with a passenger and I'd much rather have the seldom used e-brake impeded vs. having the shifter impeded. If you don't usually have a passenger, then its a non issue...
As for the original style shifter, I've used versions from 2 of the 3 companies that made them and found all of them to be vague and require a lot of shift rod and coupler fabrication to make work at all. I was less than impressed, especially for the money.
All in all, I think Ed's solution of a modified Brandwood would be the easiest route to go, albeit still not simple and requiring some fab work. I have a used Brandwood many many years ago, but we attached the e-brake directly to the side the brandwood box by welding a proper sized tube to it directly.