I know how you feel.
I made the mistake of listening to a friend instead of my gut and brought home a cat very shortly after Oscar died. My friend grieves differently from me, so bringing home a new pet makes sense to her. Me, I felt like I was betraying Oscar. I couldn't stop comparing Jasper to Oscar. "Oscar didn't do that. Oscar would sit on my lap." Stuff like that. Jasper was cute as a button but he wasn't Oscar. That was the only thing wrong with him. I took him back to the shelter, wracked with guilt--guilt I already had about putting Oscar down and guilt about abandoning a kitty who needed a home. Today I asked a friend of mine who fosters to put out a notice on Facebook about him, in the hopes he'll get adopted quickly. I met another kitty who shares a similar temperament with Oscar. He moves around lazily and plays and gets bored and self-conscious. But he doesn't seem to care for humans. I'd likely have to get another cat to keep him company. I'll be fostering him next week, which will make me feel better if it turns out to not work out. Maybe fostering could be an option for you. That way your house isn't empty and if the connection isn't there after a few days, you can give him back. It could also help you determine where your heart is. I have a mother hen personality so even though I resented Jasper for not being Oscar, I still wished to ensure he was happy, and in the short time he was with me, he did imprint on me compared with my brother (another reason I needed to take him back quickly, before he could completely imprint).
Oscar was but 9. I had not even 4 full years with him. He loved me so much. And I loved him. He is sorely missed.