Yes A7V supports the 1.4ghz t-bird part.
I am currently running the two together.
There is a 200mhz FSB 1.4ghz chip.
Here's how to make it work:
You must be using BIOS 1008 (which remaps the 5x multiplier to 14x in BIOS)
The 1.4ghz chip must be the 200mhz FSB Athlon B
The chip must be locked. Ie, the L1 bridges are broken. Most, or all, of the 1.4ghz Athlon Bs shipped locked.
It will only work in jumperfree mode.
FYI, my A7V is board revision 1.02. The 1.4ghz t-bird should work with any revision, but I can only 100% confirm it for rev 1.02.