I have recently had a similar experience to @Peterspotter . I am adopted and my birth father didn't know about me. He also has no other children (I believe it was a lifestyle choice.) Not only did he welcome the contact, he had huge plans for how I was going to slot into his life (which I sensed could over time include meeting some practical needs) and I have had to step back. It was an extremely traumatic time.
We also connected over Ancestry. (He was on there...) I ended up phoning him.
I am on several FB adoption reunion groups and there is widespread support for the idea people in our situations have the right to do whatever they need to do in terms of satisfying the desire for contact/answers.
It might well work out for you. But do not underestimate how emotionally hard the process can be. Managing him, my adoptive parents, my own family - not to mention my full time job!- took a huge amount out of me. You also don't know how his family might react. There is that factor. You might be thicker skinned than I am!
Here's another angle: after I dealt with him I understood why my birth mum fled. It was kind of overwhelming to me to see so much of myself in a person but have that view. Given the circumstances of your parents' relationship, could that happen here?
There is almost nowhere to go when these things go wrong too - it feels like a minority view to not want further contact. I felt judged.
Hope some of this is useful to you.