1971 Coupe De'Ville Heater Core Question

I am talking to a man a few hours away from me about a 1971 Coupe De'Ville he has listed on Craigslist. He says the car has a bad heater core. I've checked the repair manual that I have and it states that the 70-76 Seville, DeVille, and Brougham heater core replacement requires the removal of the dash. The seller tells me that he has had it to a mechanic and that he tells him it is a "simple fix" that can be done from the engine compartment without pulling the dash. I have searched the forum and found some discussion on the subject on other years but no real clear yes or no answer as to whether or not it can be done with out removing the dash. Any addition information would be appreciated.

Thanks,
James