@Shaark92, welcome back!
Mooney went with electric flaps and electric gear on all models in 1969; starting around 65 or 66, they were optional. My C has both, having been built in 1970. The J emergency extension is like a lawn mower pull cord behind the front seats somewhere; my C has a hand crank in the left sidewall, rather like old car windows, and was used on all Pre-J models up into the mid-70s I think.
I used to visit a 2000' grass strip on the riverbank, with a slight curve in it (I41 in West-by-Gawd, Virginny); for me, it was two people and half tanks, or solo and whatever fuel I had. When I go to the beach, inuse a 3500' grass strip that is often not fully mowed, with a displaced threshold landing towards the water. But to have my own runway would be great!
A J is just a grown up, more modern C. Fuel injection, aerodynamic cleanup, and five extra fuselage inches each for back seat legroom and baggage behind the back seat. The front seats and legroom are the same.
Some Js do have extended tanks; the C has 52 gallons, the J has 64 gallons, and extended tanks go up to ~100 gallons. But you'll have to look for one, no idea how many were done.
No idea on value, so much of that depends on avionics that are in the plane. Some more knowledgeable folks should chime in on that.
But 630nm should be doable in a J non-stop, depending of course on the winds aloft.
Good luck and happy hunting! There's a lot of Mooneys in Texas.