What makes using OBD2 system, so much better than OBD1

I'm just looking for a stock OEM EFI system to put into a restomod mid 50's wagon. I want to use a 5.2 mag/ maybe a 5.9 mag, and want to have a overdrive 500/518 trans. Modern systems. Not really looking to change cams/injectors etc. But if the OBD2 and the RE series trans are a better system in the long run. Those days of looking for big HP are behind me..I'm OK with that.

You need to buy a wrecked OBDII 1500 2WD Dodge truck.