Welcome along!
The crown vic engine will swap out fine. There might be a few swap over issues like different bolt sizes or different belt routings but nothing a weekend wrencher cant handle.
Im assuming by your screen name your new found project is an 02 model meaning it will have an 8 bolt crankshaft and the crown vic will be 6 bolt crankshaft, so a simple flywheel/flex plate swap will need to be in order along with a pilot bearing for the vic engine if yours is a maual trans.
Just note that the crownvics cams are not the same as mustangs, despite what the internet tells you. I have mapped many stock camshafts from most of the modular platforms and have found the camshafts are model specific. Mustangs and 5.4l trucks getting the best performing modular cams. Their wont be any tunning issues, just a slight reduction in performance.