Can a D-A Front Derailleur (Shimano FD-7410 8-sp) handle a triple chainring? Can't find any solid info on it.

You mean FD7410? It's not designed for triples. I suspect the cage isn't long enough to handle one.

The cage of the FD-7410 was only designed to handle a chainring range of 15T, so it's not really appropriate for a triple, even if it had the cage throw. Shimano's triple compatible, road front derailleurs from this era were the FD-A553 (RX100) and FD-A410 (RSX), which had chainring ranges of 26T and 20T, respectively.

There is a 7700(9 speed)Dura Ace triple crankset. I don't know the model number, but there's a front and rear derailer to go with it.

Thanks for the info! Appreciate the help.

That would be the FC-7703, FD-7703 and RD-7700-GS, respectively. There was also a dedicated triple bottom bracket (BB-7703) and STI levers (ST-7703). By that time, all the Shimano road groups had the options to run a triple crankset.

For whatever it's worth- I could not get the DA 7803 to play nice on a 28-38-50 triple. So I used a regular, double, DA 7700 and it's fantastic. I've been using it in this application since 2016.

IMG_1728 by Dave The Golden Boy, on Flickr

I’ve encountered similar problems with recent Shimano triple FD’s (those with that deep squarish inner cage plate like the 7703 shown above) with triple cranks having other than the design ring difference. That inner cage plate hits the middle ring unless the FD is adjusted too high. No such problems with my trusty Campy Racing T FD’s.

I managed to use a 7400 FD on a 48-38-28 tripplized chainring set up. Shifting was, as you can imagine, not crisp. It did work though.

Shimano made a triple FD with a 50T max limit. It works great on compact triples. They used it on the hybrid 10-speed triples in the early 2000’s. I think it’s an FD-730. Identical to the 7703 but the cage is for a smaller diameter set of rings.

Are you thinking of the CX70? That's the unit that gets used and talked about for road-ish triples.

If anyone wants to pore through my attempts when I built my Trek 720- you can see where I went back and forth using different derailleurs, getting another chainring, TRYING to go back to the DA triple derailleur, failing- going to another derailleur- but *REALLY* wanting a DA derailleur on there... then finding the double 7700 works perfectly...

The Golden Boy's Trek 720 Re-Re-Re-Rebuild

I don't think so. This one.
For a while I thought it was a 7730, but closer inspection indicated FD-730.
Not a 7703, either, but holding the two together reveals little differnce.
There was a sticker on the back that said "50T MAX."

Those are excellent in my exp