This is cool. I like a lot of older stuff (like cheap freewheels), and think the Shimano STI are too much money and too delicate. Some are HEAVY too!
This was my answer to the problem:

(mtn bike shifter pods on drops)
It works well, and so far has not gotten plugged up. The levers are not hard to use normally, but if riding in the hoods, shifting requires 1 hand to move off the bar.
I saw some conversion clamps that use Shimano index/friction downtube shifters on the SIDES of the original style "aero" levers. I don't like them much though. Using old fashioned thumbies in a similar place does not feel good either. Kelly Take Offs was the name.
Old style downtube shifters seem to be hard to get new, unless buying Dura Ace or new old-stock. Do you know or have a source for new OEM replacement or used DT shifters?