If it's a 24" mill then you'll only be getting about 18" max width cut out of a 24" bar so not too much worry about overtaxing it on an occasional basis. I did a bunch of my milling with my 64cc Makita w a 36" lo pro bar, and it's still fine. Yeah, everything is annoyingly specific to lo pro setups. You need an .050 bar with a 3/8LP nose sprocket - a lo pro bar - and a 3/8LP drive sprocket. But the real inconvenience is next to nothing is available in the US. Chainsawbars.co.uk has the greatest selection of lo pro gear in the world and free shipping to the US over $180 orders - and gets here super fast - but you have to not mind ordering from England. This is the proper whole kit - 25" GB 3/8LP bar, rim sprocket, and two Panther lo pro chains.
https://www.chainsawbars.co.uk/product/snhds25-50wr-kit-2563cm-gb-lo-pro-milling-bar-kit/ It's more expensive than regular 3/8 but it's kind of niche stuff not produced on nearly the same scale is why. And if you only have one saw you want to do everything with, it's a small hassle switching out sprockets every time you want to go back to standard 3/8 gear. The other approach if you're not doing this a lot is just get 3/8LP ripping chain made up in the right links for your 24" bar - I could probably make up some to sell you - and run it on your regular 3/8 .050 sprocket and bar. It's the same link spacing, just different shaped drive links so it steadily wears out nose sprockets on a bar and drive sprockets by the slight mismatch. But takes awhile, and if it's just for the odd cant here and there, you could likely get away with it without much wear. You would not believe how fast you'll cut cants with it, that's the neat things about 3/8LP on a 60cc saw.