If you're still looking and are on a budget like me, you could consider a Gator GW-Jumbo Acoustic Case. I just picked up a discounted open box one at Musicians Friend for $92.99.
http://www.musiciansfriend.com/acces...condition=used
I bought it for my '45 Epiphone Triumph which has a 17 3/8" lower bout size, so it should be fine for your '48 L-4 with the 16" lower bout.
I do want to stress this is definitely a budget case. It is sturdy enough but when you close it you have to guide the top down and push down gently to make sure the latches line up. If that bugs you, then this is not the case for you. At $92.99 I can live with that.
There is a great case at archtop.com for 16" archtops for $299 if you are willing to pay that and it would be much better than the Gator, but it should be at three times the price. Hope you have found or will find a case you like!
