am I going in the wrong direction?

I agree, go for it. Keep in mind that it's not a bolt in swap, no matter what various vendors may tell you. Also, the 2015 Hemi / trans combo is nice but if a five speed automatic, then it came out of a cop car. The roller lifters are prone to seizing on them and then flattening the cam. Good that the repairs have been taken care of. Perform a trans service and you should be good to go.