I will save this email it will take some time. I am not sure how to post a wiring diagram on here I am sure my daughter can help with that. I can make one for an A body. I still have the 75 power wagon I did in my head. we did use the 518 automatic. I know how to do it with727 but it involves using a Manuel trans pcm to keep check engine light off. I figured to build a "stock one" then once it runs like ma mopar intended the modifications could begin. basically I laid a 75 truck diagram next to the 93 truck one and made it work. the tricky things o2 sensor placement. extra brake lamp switch( for cruise control)lock up torque convertor and you will have to use a volt meter and bypass stock amp meter because of small dart charge wiring and hi amp alternator. lastly the pass through speed sensor to use stock cable odometer.
if I was to pick an A body to tell I would need to base it on using a 727 because using an over drive tranny requires substantial floor pan modification. please let me know what you would like to see, magnum and 727 A body or magnum and 518 overdrive in the truck I did and it worked ( they would be very similar). how ever you would like to see it will be a "Book". I live in Cali and the truck moved to North Carolina I don't have any photos :-(