Pics.........honestly if the '59 body style is what is attracting you to the rig, I would rebuild or replace with same.

 

The dimensions are correct (minus the fenders) but the mounting points up front are different.
The heaters are different as is the steering column, dash, and pedals, so there is some adaptation that needs to be done.

 

Stay with the 59...please

 

You could always acquire a Repli-Tub from MD Juan. They aren't as rough but rough enough to deal with drilling and fixing errors on their body tubs. Website: Kit – Body (m) - CJ5 Early VA - MD Juan

1954-1962 body tub

 

Your biggest problem will be finding a decent 73-74 tub.

 

The tub could be made to work but as noted above, there's differences in the firewall and body mounts. Also your 59 has an under seat gas tank and the 70s Jeep has it in the rear. The fenders, hood, and grille won't work.