It'll pretty much work, but you will have no flasher/emergency switch. In the '68, it was in the instrument cluster under the dimmer switch. Not sure what it is worth, but it will definitely be worth more than a '68/69... I doubt you will find a situation where you can get a complete swap, but best of luck in trying. You definitely should be able to sell it and then come up with the funds to get yourself a '68/'69 Rallye/Charger dash. That '70 looks to be in pretty nice original condition to be honest. Also, was the VIN transferred from the original dash to this '70?

I would throw this picture in the for sale section or trade and see what happens...

Cheers,