Eddie is extremely knowledgable and very honest.
As you say, finding the right speaker will be the key as high efficiency speakers tend to have more colorations. On paper, you'd want very high efficiency speakers (100 dB/w/m or better). My guess is that the Carina deserves the best possible speakers.
Bob Brines offers a couple of single driver mass loaded transmission line speakers that could fit the bill. Transmission lines provides deep, musical bass. Bob sells plans, panelized kits, unfinished cabinets, or completed speakers. If Lowthers are your cup of tea, the LT2000 might be the ticket. And they both live in Arkansas.