I like shooting available light portraits but I have trouble getting enough light

I would like to use a monopod with some SLR's. I have a Nikon F but the other SLRs that I would consider are Hasselblad 500cm's and Pentax 67's (neither of which I own).

I don't really like the idea of mirror lockup because I would prefer to move more fluidly. I typically shoot at 1/30-1/60 with standard lenses and shorter (for my Nikon). So my questions:

1. What's a good beefy monopod for not too much money? Size/weight does not matter. I was thinking of some used gitzo off keh.com or a manfrotto if bought new.
2. Anyone have luck with Hasselblads and/or Pentax 67's at slow shutter speeds? I figured that I can test my Nikon myself and that I would probably expect a 1-2 stop advantage.