I have several things to say about this but maybe the first thing should be that it will be very difficult to make these cars (those with quarter windows) safe from theft. All you have to do is cut the rubber gasket around the quarter window, pop it out, and unlock the door. That might not be obvious to everybody but I think you'd have to assume that a motivated crook would figure that out.
I have heard of at least one guy who installed a similar kit (I don't think he deleted the door locks though) and I remember seeing a picture of one of the motors mounted in the door. I just did a search on this forum and didn't find it so maybe I saw it on the groups.io group.
I bought a similar kit to one day have remote keyless entry. The biggest problem I have is that with electric mirrors, there are already a lot of wires going in to and out of the door that I'll have to make some adjustments to how they route through the pivot of the door (I've already gotten rid of the aluminum tube that holds the door lift wires).
It should be fairly straight forward to hook it all up (especially if you only have window lift wires!). I might plan for the possibility that your battery might die or a wire come loose so you aren't totally dependent on the electric locks.
Edit: I didn't notice the price on your kit! You shouldn't have to spend anywhere near that! Here's one I found (
https://www.ebay.com/itm/Car-Central-Power-Door-Lock-Unlock-Actuator-Remote-Kit-2-Keyless-Entry-4-Doors/301485755573?fits=Model%3A2&epid=1639492149&hash=item4631f38cb5:g:dQQAAOSwLKhb9iiE). Some are available with an alarm siren. Some are for only two doors but they aren't much cheaper than this one. I did a search on ebay for "remote keyless entry kit" and there are lots of them.