This 15+ inititial timing is for hotrods. You are not going to want that in a 1 ton. But what you describe sounds like the cam is way off. It sounds like you bought a multi key-way advance/ retard sprocket kit. It sounds to me like you got the cam off somehow. One easy mistake is to use the wrong timing mark on the lower sprocket with the wrong key. The other mistake someone made is they tried to put the keyway at top instead of the mark. I'd start with checking cam timing. You can estimate this "in the rig." Read the shop manual which you can download many of from MyMopar for free
If you can "guess" what the cam specs are, you can estimate the no1 valve events degrees. There are various ways of doing so at the balancer, even measuring with tape and coverting inches to degrees rotation
If the distributor advance is not stuck, and has a stockish torque / truck cam, that engine should run decent at low speeds somewhere 5is to 12ish BTDC depending.
Load on the engine/ truck weight, engine temp, fuel, etc can affect, and "it might ping" if too much
