Ok, I've been pondering this a bit and thinking about what I'd do if it were my dad.
Taking into account the heavy smoking habit and that he doesn't seem to have a strong desire to quit, I'd have to make it extremely simple for him to use and to stick with.
I'm just throwing this out there for consideration. I'm not saying "this is the only way you'll get your dad to quit smoking by using PV's"
First, I'd get him one of
these with 510 threading. See it in action
here. Advantage: plugs into wall, no recharging, 5 volts delivered to atty/carto with every hit.
Next, I'd get him lots of pre-filled Menthol cartomizers for the 510 with 24 mg of nicotine. Advantage: His favorite flavor, enough nicotine, ease of use. Screw it on, push the button, draw on it. Boge cartomizers are good cartos. I'd contact the owner of
this business and try to arrange for a bulk discount on prefilled cartos. If he wouldn't go for it, well there are other business that sell prefilled cartos for the 510 and they all have a "contact us" button on their websites, if you get my meaning.
I'd also give my dad a coffee can or something and tell him to toss cartos in it as soon as they start tasting weak. NOT when they taste burnt. Tell him as soon as the flavor, hit, whatever, drops off, throw it in the can and screw on a new one. Why? You're gonna get
some juice and refill them for him using the
condom refill method. You live close by, I hope.
Anyway, that's the approach I'd probably take. If I could get my dad vaping and liking it, portable battery kits would follow. I don't know what your budget is, and I didn't take that into account. Like I said, I was just thinking "how would I do it?"
Ultimately, whichever way you go, you're doing an awesome thing by trying to help your dad. I hope you're successful.