Tempted as well by the swap as I have a set of 7400 in the loft. They aren't mint but good condition and also have new resin decal for them too.
Let me know how you get on and if still wanting to see them I will send some photos.
Good your sorted
I prefer the downtube shifters on most of my bikes, though do have 9 speed Ultegra triple STi on my Merckx and they have never missed a beat.
I'm sure you will like the 7700
Cheers