Headlight replacement
Moto Guzzi V700, V7 Special, Ambassador, 850 GT, 850 GT California, Eldorado, and 850 California Police models
Updated:
Charles Hamer provided me with the following information in a private communication. In Charles' own words:
You can basically fit any 7 inch sealed headlight in our Loops. Be careful to bend a little the wires at the headlight plug otherwise it will knock fuses out of the fuse panel, it is a very tight fit.

Photo courtesy of Walmart.
Carl Krall has recently sourced a great headlight that accepts H4 halogen bulbs. It fits in the available space well and puts out a lot of light. It is also well constructed of metal and glass. Good stuff! In Carl's own words:
I found what looks like the same headlight as I got at the local truck stop...Amazon.com: Rampage 5089925 Halogen Conversion Headlight Kit. They are sold elsewhere under that brand and part #. All metal and glass, shallower than many so it doesn't hit the fuse panel.
The original one I bought lost its nose cone, truck stop replaced it no problem. I notice that they are popular for jeeps so I think it was an anomaly. It still worked very well without the nose cone, but did have some blinding spots along the edges which might have affected other motorists.

Photo courtesy of Summit Racing.