I am not a DK fan and my purist attitude doesn't extend to Donkey Kong. I am also somewhat lazy, desire more playable cabs and am way behind on my projects.
I provide that information as a preface to what I intend to do the next time I come across an empty DK cab
- restore the externals with authentic Nintendo gear, including that itty bitty joystick made out of Strongtanium(tm)
- wire the cab for JAMMA using a "normal" arcade switching power supply
- grab a Happ VisionPro CGA monitor (or correspondingly inexpensive arcade monitor)
- drop in a 48-in-1 with just the 3 DK games selected
Voila -- lazy man's MultiKong. You don't get D2K, but I would only run D2K using the "real" kit or the ArcadeShop board as those are the only ways that Jeff sells it (the JAMMA wiring plan is actually intended to use the 48-in-1 as a stepping stone to the more expensive AS option down the road).
Alternatively, you could use a spare PC power supply (the 48-in-1 has a connector for this), a VGA monitor (also has a connector for this) and PC speakers (also has a connector for this). Based on what I have lying around the house (which includes those three components), that would definitely be the cheapest option.
IMPO, as far a resale goes, if you use a 48-in-1, your value goes way up, compared to going original or MAME.
EDIT: I should mention that part of the above comes from not wanting to deal with the 100V issues with Nintendo cabs and the video inversion issue with original boards. If I came across a cab with a nice EZ-20 already in it, then my answer above might be different.