They are the same size as the US spec sealed beams.
Here's a link to the actual product rather than a vendor. BTW, I only posted that vendor link after checking whether the lights were in Pelican's catalog... I don't know how much interest there will be for these, but I'm thinking that these would be about as easy to install as an H4 upgrade (with relays).
http://www.sylvania.com/xenarc/x60246054.htm