For fan switches I *personally* would stay away from adjustable ones.
Nothing inherently wrong with them, but why run one if you know the temperature range you want to operate in? (thermostat governs that anyway) I would guess no one goes in and changes it once it's set, since again, unless you change t-stat, you are wasting your time.
If you can handle "stock" temperatures, one out of a Buick Grand National, probably 1987, (check thirdgen.org for part numbers or recommendations) is one that comes on at a pretty low temperature, like 195*. 220* is a little bit too high IMO. 210* would be about perfect...you don't want to end up with the fans cycling all the time.
The secondary fan switch for a late 80's Camaro comes on at 240*, so obviously GM used many different ones.
Napa's "Echlin" catalog with the temp switches, oil pressure switches, etc., is INVALUABLE when looking for switches. Typically has the on temp, what threads it uses, and how it's wired, if more than one wire. If you go to Napa and say you want to browse through it, they will let you. Connectors get out of the wrecking yard.
You can wire them both up so they come on at once, but from my experience so far, in the "heat" we have, one fan is more than adequate, so I've got my secondary fan wired up as a backup...no reason to load the electrical system if it's not needed.
Those fans you are looking at, do they come with connectors? If they are "odd" connectors, you might have difficulty wiring them/keeping them connect if you can't easily get the right connectors. Same deal as the switches I suggested above...the pigtails usually cost $10-15 when the switch itself is usually $8-10.
For the relays I'd look under the hood of any late 80's early 90's GM product. The big oval shaped ones seem to be very stout, and the 80's/90's Camaro's and I think '88+ C/K trucks came with two of them on a bracket, which makes for easy mounting. Just cut the wires off and you've got the connectors for them as well, which are water resistant.
Don't know what tools you have access to, (I'm guessing more than I do heh) but I've got soldering stuff, some wiring, shrink wrap, and a little bit of experience wiring this stuff up if I can render any assistance.