If you decide to use the viper engine you might try contacting hotwireauto.com for the wiring harness. They did a pretty sweet job on the harness for the srt10 motor in my dakota.
-jon
70 challenger convertible. 340/5 speed. blown, intercooled, efi, blah blah blah
71 valiant scamp 318/A833OD/AC/PS
00 dakota RC 4.7L 5 spd autoX'r. SRT10/T56 swap in process
73 W200 Power wagon, PTO winch, 4 spd