I know this probably isn’t what you want to hear and might be long, but I feel compelled…
I decided I wanted another cat as a companion for the exact same reasons. Fiance had had his cat for 10 years (he’s 11 now), and he was EXTREMELY vocal, clingy, and downright non stop complaining if someone was home and not petting him. We love him to bits, but when I did at home schooling it got to be too much. He had lived with several other cats in past few years, of all genders… so we decided to get him a friend.
We went to the humane society and picked him out a super sweet male cat of comparable size (they are both males and huge, 20+ pounds or so). The new cat was 6 years old.
We brought them home and followed the recommendations of gradually introducing them, etc. Since then, both cats have developed territorial issues of urinating/defecating on the floor, our clothes, anything the other one touches. The new cat just wants to play but our older cat HATES him and refuses. Fights ensue. We bought Feliway (a cat hormone diffuser, similar to a glade plug in, that is supposed to help cats get along… extremely expensive) to help them get along. It reduced the amount of urination and fights, but after a year and a half of living together, they still don’t like each other. They still fight and have litterbox issues.
Older cat previously never had peeing issues, ever.
If I could go back in time, I would have just dealt with his loneliness or only gotten another cat if I could have returned it to a breeder or something if they didn’t get along. But now we are stuck with two cats who hate each other, and I can’t in good consciousness send him back to the humane society where he will probably get killed. So, I would seriously consider if your cat’s loneliness is bad enough that you can’t deal with the worst case scenario (your house smelling like cat pee for life and two cats that hate each other), unless you can find a flexible way to see if they get along and return the other if they do not.
I thought we were doing my older cat a favour in easing his loneliness… but now he’s just miserable.
PS. He is MUCH less vocal with another cat around though. I would still do anything to go back and deal with excessive meowing than the issues we have now.