If it is not too late I have a smaller one of these for a Paul McGill nylon string guitar:
http://www.sagamusic.com/products/pr...spx?item=TL-50 .
A 1948 L4 has a 16" lower bout. Should be a good fit.
Otherwise, a Hiscox Pro 2 GAD-Dreadnaught fits an ES-175. Bought directly from Andertons UK it is about £109 plus £17 postage!