Did engine swap and now it will not drive anywhere?

So, I just did an engine swap on my truck listed above. I pulled the old engine with the transmission and separated it when I got it on the ground, I then took the same 5.3 engine out of a 2011 Silverado and bolted it up to my original transmission and set it back in. Hooked everything up and started it. It sounds like a perfectly good running motor until I gave it gas and the idle wouldn't come back down below 2,500 RPMs, so I figured vacuum leak of some sort. Anyways, I think I got that issue figured out but then I tried it again and put it into gear and there's nothing, no reverse, no gears nothing. So, I put it up on jack stands and put it in gear to see if torque Converter would spin with flex plate. Which it does I do t think the transmission fluid is circulating though because the level on the dipstick stays the same. I don't know where to start from this. Do I outline the whole engine again and go from the start or is there something I can do to fix this without pulling everything apart again?