Do you realize how confusing that would be? GTX 780 Ti would be a guaranteed B revision but GTX Titan and GTX 780 would be a mix of A and B. Then you'd have some retailers sorting A and B cards and marking up the B cards for a premium price. I know this is done to an extent with revisions of CPUs for overclocking ability, but very few retailers ever do this, and as far as I know there have never been major feature changes on different silicon revisions, only minor errata fixes.
Completely out of curiosity, what heatsink did you use that only cost $40? The Accelero Xtreme III that everyone is recommending starts at $75.
Well, it's a bit ugly though
http://www.ebay.com.au/itm/Gelid-So...o_Card_GPU_Cooling&hash=item19e4830891&_uhb=1