In regards to the viscous fan, I had a 7-blade fan that bolts to the viscous clutch laying around and I went to the parts store with the measurement of the distance from the front of the water pump pulley to the radiator (minus 1 inch for fan clearance).
The guy behind the counter will probably need to dig out his books for Hayden or whatever they carry for viscous fan clutches, but we started with a non-thermal viscous unit for a mid-80s Dodge pickup. We went through the catalog and found one with the correct length. I had him order it and it showed up the next day.
I can't remember the part number we wound up with, but the fan is right at 1 inch from the radiator and this sucker moves a lot of air. I may end up going back for a thermal unit because I have problems keeping the car warm at the track...and this is without a shroud.
The only problem I've had with the viscous units is when I pulled it off last year, I set it flat with the flange that mounts to the water pump face down. I threw it back on the car in a couple of weeks, I started having overheating problems in traffic. I found out that this is a big no-no because they tend to leak when stored this way and I had to replace it, otherwise it's been trouble free.
Total cost was about $25 or $30 for the clutch and the fan was free cause I already had it on hand. I wouldn't think one from a salvage yard would be very expensive, you'd just have to make sure that it rotates the right way.