Andy,
I've found a plan for a child's spindle bed in my book of reprints of articles from Gustav Stickleys The Craftsman magazine. The dimensions are as follows:
Headboard: 4'4"H, 3'W (2" x 2" posts)
Footboard: 3'4"H, 3'W (2" x 2" posts)
Distance between Head and Foot: 5'6"
Internal width for...