Replying to two posts above:
1) My memory of what I've read is sketchy, but there were at least a 5x7 and a 6-1/2 x 8-1/2 back originally available for this camera. The latter had an extension built onto it, with swings. You can see pictures of the camera at www.glennview.com/vcam -- go to the page and search for "4x55x7 Toyo Field Camera" (no quotes). There are two groups of photos, and the one showing the larger back installed is the last one, at the bottom of the second group.
I had thought of modifying this camera to make rear swings for it, but decided against touching it because of the tolerances involved; I couldn't figure how to do it without modifying the basic geometry on the thing, without actually modifying the bed at the back, and I'm not willing to do that on one of these; they're rather rare.
2) The camera uses the same lensboards as the Crown Graphic, and later Speed Graphic. These are plentiful used; rarely you can find one undrilled for a price. Also, there are after-market boards made that are pretty reasonable, and would save you having to pay Toyo prices. These pop up on eBay from time to time.