Many print films have enough latitude to produce decent prints if
underexposed by 1+1/3 stops, which is what you'd be doing. If you want to
actually "push" the processing of the film, most "corner photo marts"
won't be able to do that. (Doing so is also a second-best option.)

Are you sure you can't find faster film locally? Most drug stores in my
area seem to carry ISO 800 color print film, albeit often only in
12-exposure rolls. If you have a real need for this sort of speed but
can't find the film locally, I'd mail-order it. Since your IP address
suggests you're in Canada, you might want to check out Henry's
(http://www.henrys.com), which is in Toronto. (I'm in the US, so I don't
shop there often.) The US-based B&H (http://www.bhphotovideo.com) ships
internationally, but I don't know how product and shipping prices would
stack up against Henry's. My experience with mail-order film within the US
is that the film is much less expensive than locally-bought film, with
better selection from the big mail-order retailers. Shipping gobbles up
the cost savings and then some on orders of just a roll or two, but if you
buy several rolls or if you buy film plus other things, the shipping cost
is manageable.

That kind of film is going to be pretty grainy. If I were you I would
shoot Fuji press 800. You can buy it at B&H or Adorama and have it in 3
days. You should be able to find Superia 800 locally.
smitty