Well, I think you've made a rational decision. One thing you'll have to remember though, the FOV is really small with a C-14 and a ST-7. Your pointing accuracy would need to be dead on, otherwise, you'll get frustrated really quick.
Here's some FOV calcs:
8" LX-200 @ f10
ST-7 FOV: 7.9 x 11.8 arc minutes
8" LX-200 @ f6.3
ST-7 FOV: 12.5 x 18.8 arc minutes
14" Celestron @ f11
ST-7 FOV: 4.1 x 6.1 arc minutes
14" Celestron @ f6.9
ST-7 FOV: 6.5 x 9.8 arc minutes
Now, in a couple of years you may be able to find a ST-8XE camera for the price of a ST-7 now. It will give you 4x the FOV.
But I will tell you, at these longer focal lengths, you better consider purchasing a very accurate mount if you want to be successful at the longer focal lengths-- it's by far the most important part of an astrophotography setup.