Wow oh, you're 84 years old. I'm 68 and retired. The job that you are qualified for, which would be full-time, again, with your background it's going to put you way over the amount that you were going to have to pay taxes on including your Social Security. Your kind of experience can't be matched.
Go to all the local shops in your area as far as you can afford to drive and introduce yourself and see what you can do about getting some off the books or 1099 gigs. Chances are if you never report the income you will be okay. Especially at the amount that I think you're getting as Social Security at your age. Unless you're not telling us about some huge pensions you're getting. Good luck to you!