This does present a challenge. To get a PV with a decent amount of battery life for a very heavy smoker, you almost have to go to a non-cigalike battery. Are there any brick & mortar shops within driving distance where he could try some different configurations out before buying? How big is TOO BIG FOR HIM needs to be determined. He likely won't even try something if it's appearance is not to his liking. You may need to suck it up and find the best cigalike setup that you can find.
For someone who has invested so heavily into smoking their entire life, giving it up is like giving up an old friend. Cigarettes were always there to provide comfort during times of stress. And giving up smoking will likely be stressful for him as heavily as he was smoking. These types tend to be very stubborn and resistant to change. I hate to be pessimistic, but the best you might get out of this adventure is to get him to cut down on his smoking, which would not be a bad thing at all. As we say here, it's not the number of cigarettes that you smoke that counts, it's the ones that you didn't.
My suggestion would be to get his foot into the door with the E-roll. Perhaps after a period of time he may see that vaping could help him quit, or at least become a part-time smoker. He'll also likely get frustrated with the inadequate-for-his-needs battery life of the E-roll and be ready to consider something with a higher mAh. Perhaps an eGo for the next step in progression. Like most of us, we start out small and see that it works, and move up the ladder for added convenience. I think you will need to take baby steps in this situation to be successful...if at all.
And above all else, he needs to WANT TO QUIT. Otherwise, you both will be wasting your time.
Edit to add: Is your father seeking medical care for his chest pains? This sounds like angina and heart disease and giving up smoking will not cure this. He needs to be under a physician's care and STAT!