Easy way to upgrade OBD I to OBD II

Upgrading from OBD1 to OBD2 on a Magnum equipped truck or conversion project is easy because most of the connections are the same for sensors and outputs.
Basically, just get an entire harness and the ECM from an OBD2 donor truck and install it on yours, then add whatever is missing, such as downstream O2 sensor.
Take pictures of all connections on the donor vehicle as you unplug them, and maybe even use masking tape to mark each connection for where it goes or connects to.
The biggest thing to watch is if your engine has an egr system and the donor does not, or your truck is hydraulically controlled transmission and the donor has the electronics.
Syked ECU tuning appears to have easier to use menus than SCT, but I have not personally tried Syked ECU tuning yet. I know that SCT can turn off the electronic transmission controls.
Finally, figure out what injector style (the connector itself) you want to run with your modifications and get a harness that has those connectors already on it, to save some work splicing or using the adapters that are available.