Here's one possible answer for you -- a Spyder brake on a different kind of mount. I have 914-replacement discs in the back, so this pulls the e-brakes on both sides.
The perch it's on is a three-inch piece of my front beam, welded to a couple pieces of bar stock. The tunnel cap was something I came up with to close off the old e-brake's gaping hole in the tunnel. The old brake looked kind dumb with no carpet around it.
The repro 550 brake assembly was stupid expensive ($500 USD) and the metal's really weak. I have to be careful not to bend the handle when I pull it.
There are other options, but this was what answered the mail for me at the time.