Look on swing sites and craigslist. Take pictures of her faceless and naked. Neutral background and post them with your area code or area in the ad. Have the email replies sent you your mail box, not hers. That way you can screen the responses, weed out phonies and find someone suitable without risk to her. Have pictures available and set your conditions in the ad such as, "bareback only, clean bill of health, condoms only, regular bull, unmarried bull, overnights, etc"
After you weed out the phonies and have selected a candidate show him to your wife. See if she finds him compatible and his equipment is large enough. If by now he hasn't sent a face and cock picture, he's fake.
If she likes him,
Then call him on your phone and or text. Get to know him and make sure he sounds genuine and stable. Lastly meet him briefly in a local parking lot and make sure he's real. Just long enough to shake hands, chat and leave.
After that meeting if it all feels right send him an email inviting him to meet you both for a drink or dinner and chat.
Wife should wear no underwear and dress nice. You should take a back seat to the conversation and just listen. Let them get to know each other. If all goes well you can quietly lean over to your wife and ask, "do you want to invite him back to the house (room)?"
Let it be her decision.
Lastly, sometimes his clothing may not impress you. You might thing he could have dressed better or what's with the shoes? None of that matters. Some women like the gangsta thug look in their bull, others like the suit and tie business man look, again it's her choice, not yours.
Seems like you have "sparked" her interest . Thats always a good first step . Now , you need to think , a lot , about where things go from here . Are you looking for a "LTR" ( long term relationship) or just a ONS ( one night stand) ? Usually , different guys qualify for one or the other . In either case , it needs to be a guy she likes.
So , SHE needs to scan the black guys in the "population" for one that makes her hot . Then make arrangements for a meeting so HE is also interested in HER . Having made the introductions , get out of the way and let nature take its course ...and it will ..