70 fit a 67 ? Non AC Heater box

The heater cores are different part numbers, although the firewalls are listed as being the same from AMD for non-A/C cars from 67-76. I don't think that's totally accurate though.

The heater controls are different though, they changed the directions that the cables pulled and how they were mounted. There are ways around it, but it's not a bolt in deal. I use an earlier rallye dash on my '74 Duster, and mating the controls to the heater box was a bit of a problem. The heat control is hooked up and works, so I can control whether I actually get hot air or not. But the location selector doesn't (defrost, floor, mix, etc), it's not hooked up. I set my controls on the box so my defrost always gets air (daily driver). I know there's a way around it, but when I was under the dash actually hooking it all up I decided I used "defrost" over 90% of the time anyway and stopped giving myself a headache over it. And I haven't revisited it since. @RedFish would probably have a better idea of the problems you'd encounter and how to solve them.