Dodge D200 Sweptline Engine Tranny Swap.

I'm building a 1963 Dodge D200 Sweptline truck. I have a Mopar Magnum 360/380 crate motor connected to an A500 4 speed automatic transmission. This system was donated/sponsored by Daimler Chrysler back in 2000 and then it just set on the shelf until this year. My plan is to use this setup to power my D200 truck. My question is in regards to the A500 tranny. The truck will be a daily driver but occasionally it will be used to tow my classic cars to shows 200-300 miles away. Is the A500 tranny suited for towing or do I have any other options for a 4 or 5 speed automatic transmission without a computer. I have a 1955 Plymouth wagon with a 5.7 Chrysler HEMI with 545RFE tranny, which we love but everyone tells me the 360/380 Magnum is possibly a better motor that the 5.7 HEMI. Any suggestions on the tranny for the Magnum engine would be most appreciated.