If it was my decision, I wouldn't hesitate to go for a well cared for 4/4 Sport (2008/2010) rather than something like a 1975 model.
Yes, it's almost twice the price of your 1975 example, but you'll get your money back if you sell it and in the meantime, you'll have a (imho) better car to drive, Less to rot & less to rust. Less to wear out so quickly (due to age). Better fuel economy for the same performance etc....
Less time under the hood = more time out enjoying the drive.
If you can stretch the budget to a newer 4/4 with the Mazda 6-speed box, then all the better!