Fretless Wonders should be pretty unmistakable because they aren't crowned at all, they're totally flat like a staple.
Here's a picture of some new old stock Fretless Wonder fretwire (so we can rule out any play wear), and you can see they're basically a T shape.
It's only due to years of play wear that anything other than a Custom would look close to that.
I seem to remember playing one of those. Made some friends over the phone at GC in Nashville. This summer i'm planning an over nighter there. Check out GC and go to the Gibson plant for a tour. GC is gonna set up a firebird and a late 60's SG custom for me to check out. Put some .008s on em. I'm not worthy! Guessing they have a huge store and inventory on display. After all, it is Nashvillle. Those guys there are so cool.
I know, I will be taking pics to share. Otherwise, "it never happened".
For me guits have to first feel good not plugged in and of course play well to the hand. Construction wise, save specialties like fender, guild gretch, and the like, i prefer, bolt on, set, and neck thru as the best.
In Nashville, the young kid in me sees myself hanging out on a sidewalk w my accoustic playing the blues.
Gawd, i learn so much here.