Nice. have you cut a hole in your floor yet? are you happy with where that shifter location is going to be? I'm putting a viper spec T-56 into my Dakota, and I converted the front inspection cover to be a shift location using one of the kits on Ebay. it allows the shifter to move forward about 8" while still retaining the reverse lock-out feature. I believe the Magnum T-56 comes with this "conversion" already done, so all you have to do is buy the shifter mechanism itself.

Also, For reverse lock-out, I'm wiring mine into the brake light switch. When I step on the brakes, I'll be able to shift into reverse. I can't think of any situation where I'm going to be on the brakes during the 4-5 upshift, so I figured that was the easiest way to make the reverse lock-out "automatic" and seamless.