Tom,
Stunning work my friend! Some of your photos look like my set, as I had my car restored nearly to your level in 1999-2001.
Regarding your horns--I developed a way to create
perfect Bosch horns that will befit the fine car you have. Since you do all this kind of work yourself, here's the plan.
1) Remove your horns, disassemble, and set aside all but the two halves of the case. You do need to pay attention to some rivets which need to be drilled out.
2) Bead blast the case halves, paying attention not to destroy threaded components.
3) Powder coat to glossy black.
4) After cleanup, re-fit the electrical block on the back half.
5) Obtain a new set of Bosch horns, hi and lo tones. They can be had at most Bosch dealers, or look under all the mail order parts guys for a set for a 300SEL.
6) Using a good quality paint, spray the FRONT parts of your new horns so they too, have a glossy black finish.
7) Using your best tools and imagination, install these new horns INSIDE the rear case of your old horns. Yes they fit. You can use a strip of steel, and existing holes in the case.
You need to take the new horn's power to the power block in the old horn. Once you have it all apart it will be obvious.
9) Use either foam tape as a gasket, or fabricate a gasket out of cardboard or craft foam for the two case halves.
10) Obtain a horn kit from Stoddard Imports
http://www.stoddard.com/ they sell a horn dress up kit which consists of new tags and new hardware. Not 100% perfect but pretty darn close.
11) Reassemble.
Your horns will be so beautiful you may not want to install them but for shows! I'm partially through this project myself.
Michael Salemi
1969 280SL
Signal Red w/Black Leather
Restored