Lots of great advice. I've never mounted one vertically, but I think I'm going to since I'll have so much bench space in the new shop (not sure how many years you're allowed to call your shop, "new"
).
Normally, I would be the first to recommend the rotating head vise that Brian posted a link to. I've been really vocal about how handy they are, especially with a simple little fixture for holding knives while doing handle work. However, Angi and I recently went into a HF and I looked at those vises because I want another one. The new version is so cheap and crappy looking, I don't feel like I can recommend it. :grumpy: :foot:
I bought mine in 1996 for $35!!! And I'm sure it is at least twice the weight of the new version.
So if you can find an older one on CL or ebay, that would probably be your best bet.
When I bought my lathe and 9X42 mill, there was a small welding table there with a rotating head vise that had 6.5" wide jaws, and weighed about 120#. It was a Ridgid made vise, made in the 60's. I damn near begged the guy to sell it to me, but he never did for some reason (he wasn't using it, it had been his Grand-FIL's!).
For a high quality vise, your best luck these days is going to be CL, an estate sale, or something like a fab/welding shop being auctioned off.