First thing you should go here:
http://www.nielsens.com/default.aspGo to 'Shopping', then use the dropdown menu to 'OEM Parts Finder'
From there, follow the prompts and find the fiche listings for your '72, and get a part number and diagram for your headlight shell. Then, compare with the same parts diagram under the years 1971, 1973, 1974, etc etc. You will find that quite often the same part that was used on the CL350 were used again year after year, and also on other Honda models year after year as well.
After you have figured out what range of years and models used that headlight, go on Ebay, or post a 'want' on this site. I would look for a complete headlight, thats usually how you find them.
HTH