Wow, that's pretty generous. Let's see here.
I agree that Winterscale would have approx. 50 colonized systems, and probably in excess of 200 colonies spread through those systems. I'd give him 100 ships, of which 1 would be his grand cruiser, 3 would be cruisers, 6 would be escorts, and 90 would be various sort of merchants and raiders, all working on various endeavors. He probably has a dozen Wayfarer stations, too, and maybe some that are larger. He would probably have an equal number of ships working for him: chartist captains, mercenaries, privateers, outright priates, other rogue traders, maybe even xenos.
I'd put Chorda at around 100 ships, also, but her battle fleet would be much smaller, probably her cruiser, a couple light cruisers, and 5 escorts. The remainder would be mostly frigates, destroyers, and raiders, though there would still be some merchant vessels. Her "empire" would probably touch as many, if not more systems, than Winterscale's, but instead of colonies she'd have trade stations. A lot of her business in the Expanse would be "extralegal." According to the sources, much of her wealth is still tied up in other sectors and endeavors, so her overall wealth in the Expanse would not rival Winterscale's at all. Also, she'd have as many "hireling" vessels as ships in her presonal, private fleet.
Saul would be my spoiler. He'd have nearly 100 vessels, too, and they'd all be merchants, every single one of them. He hires his guns, which means that he has a higher profit margin. So while the Big Two have the glory currently, Saul is catching up and passing them, hoping they will go to war with each other so that he can pick up the leavings.
Given how my PCs treat ship acquisition, and that these two dynasties have been established for awhile I wanted them to actually be representably powerful opponents. Their fleets are composed of the Rogue Trader, Free Captain and Raider groups they have defeated and absorbed into their empires. They're not particularly loyal though, so how far they can be counted on is hard to say.
Transports I feel are actually quite plentiful, so I imagine Saul's fleet is even larger than that, but has the slight problem of not having as many available guns. He would likely be able to buy the loyalty of a large number of these fleets.