I'm no Leitz anything expert, but I own and use a iig.
From your photos, i would rate this baby as Good 5.5-6/10. It's I believe it's an early postwar iic, and it looks as if it has seen some use in its time. The leather seems okay and I don't see any rust or tarnish on the metal, also good signs.
The '50 Japan lens I know nothing about. But that '135 Hektor, sighhhhhhh - it's an old one, maybe early 1930s, and if it's in fairly decent condition with clean glass, on the collectors' market it may be worth about what you would be paying for the entire kit. Prices for those lens are what a buyer will pay for it, so do guide yourself accordingly here.
The Leitz turret viewfinder (the VIOOH) is a godsend, it will make the camera usable for you as the small viewfinders can give you a permanent squint. I had an as-new one in the '80s and stupidly sold it. Looking for one now for my iig. Prices (in Australia) are way over the top, and nowadays importing one from North America or Europe isn't an option thanks to our third world ($0.64 US cents at last check) Aussie dollar. A friend kindly gifted me a Wray viewfinder from the 1940s, okay to use but permanently stuck on 50. Oh well.
Put the camera thru its paces before you buy it. Do the shutter curtains move easily. Are all the speeds fairly accurate? As others have said you will almost surely be in for a full CLA anyway, but with the happy thought that LTM Leicas are more easily repaired/restored than the more complex Ms.
So should you or shouldn't you spring for it?? The decision is yours to make in the end but my take on this is, if you get it for $300 and it doesn't pan out for you, then you may be able to flip it on and get most or even all your money back. So no loss, and a pleasant experience.
Those old Leicas take you back to an earlier time when photography was only film, far more basic, and a lot of fun. It can also be super addictive. I bought mine from a deceased estate, and in less than a year, boom!! more Leitz gear all over the place in my kit. That happens.