Assembling a LF system is pretty much like assembling various versions of Frankenstein, or his bride, as needed to suit your whim of the moment. There are very few rules and all kinds of variations are possible.
So on to your lens.
Typically with a convertible lens the short length, your 8-1/2" here, is the norm for the lens when fully assembled.
If you unscrew/remove the front element from the shutter and the rear element is used by itself the lens will normally provide a longer focal length, say 14". Certain shutters are marked for both options.
The markings on the shutter are only accurate when using the elements that the shutter was packed with originally, which is the most likely situation. The front lens element should indicate both focal lengths matching the shutter, if not the elements may have been changed which would mean that all the aperture markings may be wrong, this is less likely but very possible.
Even lenses that aren't marked as convertible can be disassembled and the individual element groups used separately to change focal length or to get various effects. Casket set lenses take this to a whole different level allowing you to mix and match elements at will. Like I said above, there are very few hard rules in LF about what can be cobbled together. In these cases you need to do the math to figure out the f number.