Nice job cleaning and painting that frame!!!
Frame swap is a big but manageable job. I’m guessing you know about the Crown Vic crossmember for dual exhaust.
Tip from my frame swap. Driver side front cab and mid mid body mount locations have 5/8” diameter holes next to them that align with holes on the body. 5/8 rod from Lowe’s was used to guide the body and frame when reassembled. Passenger side are slotted to allow some adjustment to get it just right. “Measure until you hate your ruler” then torque the mounts to spec.
Enjoy the project.