OP, the advice to use 8AWG cable for hook-up wire is simply ridiculous!
I like AWG 21 to 24 solid core pure copper OCC wire for the tweeter with no crimped on terminals anywhere. Solder all connections. If using solid core then provide vibration relief by using cable ties or some hot-melt glue to anchor the wire close to it's termination.
https://www.vhaudio.com/wire.html#vh18hookup : Chris supplies this wire with AirLok insulation which has a very low dielectric constant, even lower than Teflon. I use it inside amps too.
For mids and bass use AWG 14 to 18 OCC copper, avoiding PVC insulation. There are many outlets for good cable.
The advice to contact Audio Envy could work, they are garnering some good reviews. I have not used any of their stuff so have no comment.
With regards to changing capacitors: I do this all the time with great results.
I am sure pesky_wabbit was well-intentioned when he mentioned ESR. This is insignificant in a crossover and can be ignored. In the formula for capacitive reactance there is no 'R" value in the equation. It is:
Xc =1 divided by (2xPixFxC) If you consider that when caps are chosen for XO duties the closest standard value to the theoretical value is used, then there is the individual driver's response, the overall response and the room's response,you will realise that ESR is a non-issue : )
Perhaps when rewiring you consider replacing just the cap/s in the tweeter circuit and while you are at if you find any white sand-cast resistors replace them with Mills or similar. Expect a noticeable improvement.