Alternative health insurance options

I am trying to help a senior. He is 73 without health insurance. He is now retired because he physically cant work anymore after nearly 40 years of working never missed a tax season, never took vacation time, hes a good man. He was a mechanic and only ever just made enough to pay bills. He just started to receive social security benefits of $1400 a month. He has no dependents, significant savings or owns anything. He is currently trying to find living arrangements that match his monthly stipend. But the most concerning is that he does not have health insurance. He only has Medicare A because he believes he cannot afford Medicare B which is about $200 month (it could be much more than this because he applied for SS retirement late) and he signed a paper to end Medicare B currently. It is my understanding that Medicare B does not include dental and vision? And also does not include medicine which I believe is Part D? So even if he gets that health insurance it doesnt seem helpful. He specifically needs top and bottom dentures because he only has a few rotten teeth left, eye glasses, COPD medication, and a full workup of his stomach because he has trouble eating. Can someone please point me in the right direction on how to help this man get the care he needs. He is located in Nassau county, Long Island, New York. 11554

I only spoke to one insurance agent at my hospital in NYC who gave me some advice. He mentioned he makes too much to apply for medicaid which the cut off is $1200 a month? He said there is something called the “spend down” which he has to pay the difference between $1400 and $900 to get medicaid? Is this correct? Has anyone done this? And does this open up opportunity for dental and vision?

The other option the agent mentioned is to reinstate his Medicare B and apply for the “savings program with Extra Help”. Has anyone done this? Does this also include dental, vision, and medication?

Can you combine Medicare B with private insurance companies to get full coverage? Also is it better in the long run to do a HMO or PPO plan? (I understand this is the difference between needing a referral or not to see specialists correct?).

Basically I am asking for the wisdom and experience of others who have been through or have seen a similar situation and how to get this man the best health insurance possible without taking away half of his already little monthly benefits. Any help is good and if there is any other information that can help please ask. Thank you.

Update:

Is it possible to ask SS for less benefits so he can apply for Medicaid? It seems the least costly option if possible.

I should also note he has a medical bill of $13,000 because he was forced in an ambulance and spent a night in the ER due to what seemed like very bad food poisoning and he didnt want to be there and he had his Medicare A but they still sent him that bill.

Lastly he did have Blue Cross Health Insurance in the 70s for a few years but he doesnt recall any information from that time with that insurance. Would it be helpful to dig into this?