The guy you need to talk to is Swordfish Steve, He’ll probably do it for you if you visit him. Best by far on this sort of thing. Doing it yourself without experience can lead to failure. I would suggest emailing him on his website … probably something like swordfish marine but I can’t remember. You want to tie a great plait I can show you how to do that. Braid to braid connections talk to Steve. I tie a good fg and have done that on some smaller reels with solid braid backing and am confident all good as  just insurance (capacity)  if pull what is 500m of nylon off. Again comes down to what you trying to achieve. I’m a scrimp but really you can’t beat hollow core and nylon topshot.. just got of pay money upfront…. But reckon is worthwhile investment. Resisted for years on my 50ws and 50s but hard to argue with… unless you tie fantastic slim knots on solid braid. As said earlier each to their own. Am old school caught plenty on 24 kg nylon on 50ws… but am being dragged into future and beaten sometimes by those that do it better and moving with times, tech and connections/ knots or splices.

Cheers!

As already mentioned, I've been an early adopter of braid. Went hollow, bought a set of DAHO needles. Bought some braid windon leaders from Swordfish Steve but with the needles, learned to make my own and have made leaders from 130lb to 500lb and even the 500 is slimmer than 300 mono.