The 'life after death' issue is relevant in so much as he may think of anything between now and then as a 'stop gap'.
I wonder though what his late wife said to him? Were it me, I'd say live your life to the full, find a good woman you can love and can love you back, with my blessing.
No doubt at 50 something @Pineapplecolada1 you've loved and lost, or divorced along the way. You too have baggage but a different type.
You will never replace his wife but love can be infinite - it's not a pot that runs empty- we can love people in different ways at different stages of our lives.
Fondness, caring, shared interests, sexual attraction are enough, without anyone feeling they are No 2.
I think you need to take this slowly. He may indeed find he's not ready so you shouldn't over think it as it's such early days.
Think of it as a slow burn, not an intense fire.