A few years ago I shot a UCSB film with a rented 16BL and then did pickups with a borrowed K-3. To our surprise the K-3 lens was far sharper and had more contrast than the Angenieux lens on the BL. Figure out what you need the camera to do (i.e. high/low speeds, sync, rev. etc.) and then find the appropriate package. Spend money on lenses! Also consider your filmstock, lighting, and telecine needs. Its a balancing act, but don't sell your project short with bad glass. What about using your K-3 and another camera when needed?
Brett