I personally hate the 94-97 dash. Its ugly, and the cupholder always gets the radio wet. Plus, I like the seats/seatbelts in the quad cab better. And the position of the humongous tweeter in the door on the infinity systems sucks. I agree that the space difference between the QC/CC is minimal. Having had both, it is un-noticeable to me. It is MUCH MUCH easier to actually use the back seat of a QC though, with the doors. Also, the elusive model is not the longbed, but the shortbed as mentioned.
They are hard to find, but not impossible. BTW, there are two 98 quad cab 12V's for sale locally, both automatics, one shortbed one long. The shortbed is almost identical to mine (SB QC 12V 4x4 Red sport) except its an auto. Its clean.