As said above, the engine rebuilding can get expensive and piston rings are available sometimes and sometimes not, but the result is worth it IMHO - and you can always use different frame.
I personally like Comstars, run them on Red tubeless now.
I would get it and open it up to see whats what.
As far as brakes, Jaguar has thread on using newer calipers on 78F forks, you dont have to go original, you can upgrade.