Has there even been a short scale 8string bass made by alembic?

I don't believe we have.

Hamer made plenty when they were around. 12 strings too.

Yeah,
Hamer did short scale 8 and 12ers as well as medium and Long scale.
To my opinion only the long scales are the real Deals. 
I owned a few short scale 12string Hamers but on the low end they
are sounding rather dull and dead. 
Greetz
Oliver (Spyderman)

I'm partial to medium scale 8-strings myself, but there's no reason we wouldn't make a short scale one as a custom order of course