I purchased and installed Fender Vintage Noiseless pickups, pots and swtich in my '74 Strat along with a new shielded and gounded pickguard. I am very glad I did this but it was tedious. My frend and I did it one afternoon. He was at some point an electronics tech and had a lot of experience and a lot of electronic soldering gear like a solder sucker (incredibly useful).
All in all we had to take turns (we are getting old) and I believe it took about 3 hours or so. We counted more than 30 solder connections, I can't remember the exact number but I think it was actually quite a few more. So it takes a while from a kit.
I have since seen offerings of pickups, pots, switch and jack pre-mounted for your convenience on a pickguard, ready to be installed as a unit in your strat. For a fee, of course. When I did the kit, the pickups had just come out and there was nothing else available. If I were to do it again I would consider spending the extra money for the pre-done one if it had good components, the Fender pickups, etc.
If you have all good shielded components already (pots, pickguard) and you are just switching the pickups, then you are looking at like six de-solder and solders, but there are other connections that you could disturb on the pots and so it is a little more complicated than just six individual connections. That would not be anywhere near as much hassle as what I did.
Dave
The river keeps a talkin'