Looking through your order you have 50 LEDs and 200 resistors - you need a maximum of one resistor per LED. Depending how they're wired there may be two or three LEDs sharing one resistor, and the value you need depends how many and what colour LEDs it's connected to so you need a GON expert to advise you here, and they'll probably need to know where you are putting the LEDs? Also the resistors and LEDs are SMD which means they're small and sit on top of the PCB. SMD is not the easiest thing to solder and if you put an LED backwards it's not easy to remove it, so I wouldn't recommend it for a beginner.
I hope you're also aware that GON has about a 5 month delay between ordering and dispatch at the moment so this is not going to be a nice summer project, and I hope you're taking into account the $47.90 for shipping? You're going to need to find some cheap keycaps to keep it under $250!
If it still seems like a good idea and you like the red switches there's nothing wrong with your plan to salvage them (and the stabilisers for the larger keys, assuming they're PCB mount) but could you sell your K95 for more than the price of buying new ones? Desoldering is tedious and harder than soldering and it seems a shame to destroy a perfectly functioning keyboard
Another option would be ordering from winkeyless.kr, I've just done a quick mock up and the price came out about the same with all the tricky SMD soldering already done, but you'd still get the fun and satisfaction of soldering the switches and diodes and putting it all together. No idea on the order delay but I've not seen people grumbling so I assume it's shorter than GONs...
