Although there is nothing wrong with a narrow front, a wide-front is so popular and increases resale value of the tractor, so I would prefer the wide-front.
I replaced a narrow with a wide front on my AC D-17 IV, and with wasn't too hard, but the hardest think is locating one in good shape. I got lucky and found a parts tractor that was complete. Given the choice, I would much rather buy and bolt on a good 3 pt hitch, than replace the front end (assuming you could find one).
In an old tractor, gas seems more popular than diesel with us novices also, easier to work on.
Just my opinion, Good luck,