This is what Eric Shea did to modify the 914 rear trailing arms to use the 911 Parking/Emergency Brake System in his 914. Below are some comments from Eric, take a look...

Hi Armando, Included are some pictures of my 911 handbrake conversion. The photo labeled "Backing Plate 2" https://pbase.com/9146gt/image/40695239 shows that 40mm brake shoe rest. I've machined a 5mm spacer to go under the rotor to use a standard 911 rear m-caliper. Please call if you have any questions. Eric Scott Shea

More helpful details on this parking brake implementation http://www.performanceforum.com/wesvann/914a/rear-brake-axle/rear-brake-axle.html (Thank you Wes Vann!) and in 914World http://www.914world.com/bbs2/index.php?showtopic=76776&hl=911%20%20parking%20%20brake&st=0 - more links http://www.914world.com/bbs2/index.php?showtopic=4909&st=20