Hi and welcome!
Great that you want to give this poor boy a loving home and a chance at new happiness!
You can find tips on what you can do to settle him in our information bundle for new guinea pig owners:
Quick " Starter Kit" Of Information Threads For New Owners
It would be wonderful if your could find him a new boarmate. The key to any happy and lasting boar bond is mutual liking and character compatibility more than age - and that is where shops and breeders fall short and sadly far too many boars end up single. Yours is clearly desperate for company.
The very best way to go about it would be by dating at a good rescue under expert supervision, so you come home with an already quarantined and healthy companion only if acceptance has happened. You would also have the support of the rescue during the settling in period and the whole life of their adopted piggy. However, this is not always possible; it very much depends on whether you have got a good rescue with suitable boars within your reach.
Guinea Pig Rescue Centre Locator
Guinea Lynx :: Rescue Organizations
Getting a baby boar might be your best option if you can't get to a good rescue, especially if you can find a preferably submissive (but healthy) one. There is a certain risk that a dominant teenage boar can cause problems when he hits the hormonal teenage months, but the risk of fights, bullying or fall-outs is not as big as with getting two babies who will hit all the hormonal teenage spikes together.
A third option would be another single adult boar as a live-alongside possibility if you cannot get to a rescue.
You can help us help you with tips if you please added your country, state/province or UK county to your details, so we can always adjust our advice to what is possible and available wherever on the globe you are. Click on your username on the top bar, then go to personal details and scroll down to location. thank you!