Could use some bottom bracket help form the pros
 

I have a cannondale synapse 7 alloy i am replacing all components. only thing left i have to buy is the bottom bracket. i know for the crank set i purchased (Shimano Ultegra FC-6703-G) requires bottom bracket SM-BB6700 (HollowTech 2). i read on another forum that i may possibly need an insert for this bottom bracket to fit. can anyone shed any light on the subject? please and thank you

Why not just get well good BB30 and some wheels mfg adapters? Working great for me.

bike likley is BB30. Use the standard BB30 bearings.
You have a couple options...maybe more. Ultegra 6700 is a great crank but designed for external bearings. No problem though and common to adapt Ultegra cranks to BB30.
Two options to look into:
1. Go onto Wheel Manufacturing's site and look for adapters. If you have any question about which adapters to purchase...email them.
2. Praxis BB. This is a nice option. They also sell many BB types. Any question about which to use, email them.

Both solutions work well. Praxis will be slightly more expensive because it comes with its own bearings...but will likely be less trouble all around....bearings are captured and sealed.

If you use the BB30, you don't have to worry about preload either. Makes for nice spinning cranks.