I'll throw this out there-I have under-the-floor Pedals too, however I am running a 7" Dual Diaphragm Booster. My engine also does not create enough vacuum, and I am running a Concept One Serpentine Pulley system which negates the use of Hydroboost Pump (I'm not sure I'd want those Hydraulic lines running that close to my Exhaust anyway, it's tight under there)-

So, I investigated about every other avenue I could find, and it presented a few choices:

1. Buy one of those electric, aftermarket Vacuum Pumps, offered by Summit, Stainless Steel brakes and the like (which I did, but I wanted to mount it under the car to keep any noise out of the cabin-these MUST be mounted upright, and, they are a bit noisy, so they were out)-

2. I found that Electric Cars use a Pump made by Hella (Hella makes good stuff), and they offer three Pumps: UP28, UP30 and UP32-the difference being the designed life (the UP28 is designed for 600 hours of use, the 30 & 32 are 1200 hours)-the other upside is that they are a Vane pump (read: quiet and long lasting), and this design allows it to be mounted at any angle-I went this way, and doubled up on rubber mounting just in case-

I found out later that these Pumps are also used in early 90's Mustang Cobras, Audi's, VW's and some GM Car products-there is another design that is used in Diesel Pickups (Ford Dodge, GM), but I don't who manufactures them-go on Ebay, type in electric vacuum Pump-you'll be surprised-

Hope this helps-