There was just a thread on this in the either the restoration or technical forum.
My understanding is that popeye will run in a DK/DK Jr. cab even though Popeye uses a different power supply. I haven't tested it yet but Nerdtendo says his worked just fine.
You'll need to rotate the monitor horzontally (which requires horizonatal mounting brackets). If your machine doesn't have the horizontal holes drilled already I'd be really hesitent to drill them. You don't see DK and DK Jr. cabs with only two holes drilled very often.
The other thing you need is a wiring harness, because Popeye uses and edge connector and DK Jr. uses the multi-connection harness. If you can find one of the harnesses Dockert & Flagg made that would be the best option. Otherwise you'd probably need to modify a DK 3 harness.
Other than that though, yeah, it should work.