I did manage to retrieve my Scorpius from my parents' the other day.
the assembled length ( end of pod to end of pod ) of mine is 6 3/16" .
not sure what length that makes the dowels, as they're inside the tubes - it obviously makes a difference where you put the centering rings / how much overlap there is .
The AR-520 is the standard centerign ring-used-as-thrust-ring, so should be consistent .
Mine is a semi-clone ( opened kit that sat for years, tube and cone used elsewhere, later built it up using a 'guestimated' tube length from the catalog ( this being prior to Jim Z or YORP ), and measuring it now I was very close since I used a 12.625" tube length
.
I believe I used the original kit dowels, as I apparently had these 8 the same length, plus original decals, etc.
If anyone has a built-up , please measure and let us know ( or if you have an unbuilt, even better ) .
~ AL
ps: the decals on that look good, like the little 'scorpius' name on the pods, etc.. really personallizes the bird.