Doug,

While I understand being frugal, I think that the Brifters are like 90% of the upgrade cost...

You can do it directly only if you find a set of DA shifters from pre-9 speed.

Otherwise, you are in bad luck... Pre 9 speed Dura-Ace used a different amount of cable pull than any other Shimano indexed shifting RDs... Every other index capable RD, road or mountain was the same (regarding pull) except for the older DA stuff. (I read somewhere that Shimano is repeating that mistake by making the newest DA pull a different amount... but probably still not the same as the old DA).

If 7400 was index capable, then look here for another alternative:

http://www.sheldonbrown.com/dura-ace.html

It looks like you can run an 8 speed cassette off of any Shimano 9 speed shifter with the early DA derailleur.

On the bright side, I think a down tube FD would probably be doable... However, I don't think anyone makes a left side brake lever with the same look and feel of a Shimano brifter, so you will probably be lopsided looking (and perhaps feeling).