It is really a dilemma you have.
Talk with your mother about him and find out if she thinks that he wants to see you.
A meeting might work out just fine
If you meet him it could happen it would be a disappointment ,you may not get a good contact with neither him nor eventuel other relatives.
He might have married and have children and for them it will be a great chock all of a sudden to get you into the family.
As a rule I think the meeting with unknown fathers or biological mothers do not work out very well. At least that is what on reads.
To contact him for DNA and health reason is a bad idea.
Imagen that the meeting is going to work out so bad you hardly can get over it.
Will your mental disappoinment really be worth it?
It is nessecary to know that you might get XX illness some time in your life and then have to worry for decades and then you do not get it.