First, measure the total width of the outside edges of the hi and lo beams including center bar. Then measure the height of one headlamp, since all 4 are the same size.
This information will help narrow down what car to get the composite headlight shells and mounts from.
(Looks like the pic has a set from a '87-'91
Buick LeSabre or '87-'88 Cutlass G-body units) Be sure to get all mounting brackets, and adjustment parts!!
Then carefully cut the center bar out of the headlight trim.
From there, you'll need to remove the headlight buckets and mounts from the core support. Install the new headlights and brackets where the old buckets were.
Keep in mind you may have to use longer bolts and spacers or washers to make the lenses line up and make it look right. So measure plenty of times to minimize trips to the hardware store.
Finally, install a conversion wiring harness to adapt the old wiring to the new halogen bulbs. DO NOT splice the donor car plugs onto the old harness. Halogen bulbs draw a ton of current and will melt wiring and your headlight switch!!
APC has good harnesses with relays built in to help keep the wiring from overloading.
Good luck with it. I'm sure others on here will have similar and different ideas.