Thank you Dennis.
I did not think to look here. Seems the usual hardware places: Ball & Ball, Horton, etc. do not make smaller strap hinges.
I'm not sure about the quality, but I did order a pair of 6 1/2 " straps for my box: http://woodworker.com/6-12-strap-hinge-flush-mssu-110-672.asp?search=strap%20hinge&searchmode=2
They offer "flush" and "off-set" hinge options, so I got the "off-set" thinking that might be better for a box lid with an overhanging lip on the back. I suppose I'll need to cut a groove in the back of the box to accommodate the hinge pin. I want the hinge to be seen on the inside of the box lid, not on the outside. Looks like the hinge will have to be fastened to the outside of the back, not the inside, to make it work.
The hardware makes the piece (or maybe better to say that it can ruin it if not done well), so I'm open to other suggestions. I sort of like the strap hinge best, looking at photos of period pieces, mostly Chester Co., PA (where I'm from).
Thanks again.
--Bill