I don't know if this answers your question but Palmer built many versions of the Thunderbird, including a round-cowl one he traveled with internationally. I held in my own hands his actual 1957 round-cowl T-Bird, in England in 2007 so know it is real. Brodak kits an earlier T-Bird with upright-mounted engine that is not the prettiest of Palmer's designs, while RSM kits the later version of the Thunderbird with inverted engine and bubble canopy that is the better-known T-Bird and most often built (at least in California, Palmer's home state). Check the stats on those two for wing area.
There is a discussion of the "differential flaps" T-Bird over on the Nostalgia 30 board right now, have a look. Universal consensus is not to build it that way. Even Palmer gave up after a short run of using the concept.