I'm got the "M" caliper rear with 20mm vented rotor and fabed up 944 E-Brake solution
. Was told Eric Shea sells the 5mm spacer washers to do this conversion , will contact soon. Will make up cables using 944 right ( long ) side cables and 914 right ( long ) side cable housings , just didn't want to use half of the 911 e-brake setup , so went in a different direction , so far all fab testing has been very positive , and should be able to use the 964 e-brake handle i scored off evilbay to setup a center console e-brake handle instead of using the stock 914 e-brake handle and cable routing.
Jaxdream