Get your dad as much life insurance as possible and put yourself as the beneficiary. At some point he will die. That's fact. And you'll inherit the amount of the policy tax-free.
I wonder what you think life insurance will do. List your needs, and there are probably better ways to met them at this point. For example, if you Dad was in the military, they have burial plots and you can get the paperwork collected for when the time comes. If he has a mortgage, see what you need to keep the home, or sell the home.
A friend once described life insurance this way, "Every year I send my insurance company a check for $400 and say 'I bet I die." They renew my $200,000 life insurance policy and say 'I bet you don't.'" I've never heard insurance explained more concisely! So, think about it. You're going to have a hard time finding a company to make that bet with an 83 year-old.
You can get him more life insurance at his age. But depending on his health, you may need to get guaranteed issue, from Kemper, Mutual of Omaha and many other companies, I can send you a referral for an agent in NY if need be, But you need to see why he needs more insurance, usual reasons are; final expense, (burial and expenses), legacy to pass onto family, help surviving family pay expenses they will now incur.
So, think about it. You're going to have a hard time finding a company to make that bet with an 83 year-old.