My honest no hater advice to you would be to pass on the 510. You have a Z near completion and youve lost interest because youve hit some road blocks along the way. Now youre trying to buy a car thats in pieces with no title. I dont recommend it. If you really want to stay Datsun, then I recommend getting your head in the game and complete your Z. If you really need help with the car, Im sure there a few of us in the area that would be more than willing to come over and tear through that car to get it back to running condition so you can daily it.
People give you a lot of shit, but this is still Ratsun... we will bend over backwards to help one of our own.
Youre going to need to bust your ass to get that 510 to daily status and a place where youre going to want to drive it. Body panels, installing engine components, all the maintainence items (if it really has been sitting for as long as you/the owner say it has), let alone what youre going to have to do to get a title in your name... If your heart isnt in it, I say pass and get something else. I dont want to see another half completed Datsun project get sold because youve lost interest again when you realize theres work involved.