I dunno if anyone makes detail sets for the L-4 or not; my guess is nada, although I haven't had occasion to look for any myself. A quick search on several online sources yields nothing.
I also looked for some reviews but all I found is a kit preview which wouldn't help you much and a photo feature of Randy Lutz's NE-1. (USN L-4) This isn't a kit review; there's a few photos and a listing of what he did to the model, but no basic construction notes. However, there is a mail link, and I'm sure you could give Randy a hollar and ask him for some guidance. I don't really know the guy too well, but he's always been an accomodating fella in answering questions at shows and such, so it wouldn't hurt to email him.
Piper NE-1 Cub
Here's a link to a page dealing with
L-4's and Piper Cubs on the
Kiwi Aircraft Images site. Some of what's in the detail shots is not original equipment that you'd have found on period L-4's, but there are some photos here which may be of use to you. And, in any case, it's just neat to look at this stuff!
Wish I had more for you...
Fade to Black...