So, after many years of trying/begging, my wife has finally come around and is willing to play.  Her one condition was that it was a pro.  I think she, rightfully, feels there's less chance of a connection.  She doesn't know the extent of my hobbying.  She's mixed, tall, and an incredible shape.  Gorgeous model type, but very conservative in bed.   She said I could pick the type so here's the ask:  Under 30, slender or athletic, mixed or ebony a plus but not a deal breaker.  Implants preferred and someone who can make her very comfortable with some coaching and role play.  The session is going to act as a tutorial where our guest will coach/show her how men really like it.  Need to break down fear so she can tap into her wild and uninhabited side.  She likes girls and has had a few experiences.  Let me know if anyone is out there who fits the bill.

i can not overemphasize a key point.   she should meet the girl alone first.  maybe just for drinks, and then the two can head off to a bedroom or even not.  so she is comfortable with the girl.   to women it matters who the person is unlike us guys !       point is you are going to have to do this in steps.  you move too fast she is going to retreat from the idea.    

this is especially crucial since this is something you are asking of her  vs the wife who is naturally curious.    
trust me will be well worth any extra donation.  and besides the same is also true for the lady you contact, she also will feel much better knowing the wife is comfortable.    girls get asked into couples all the time where the wife backs out or is obviously unhappy .

Great input!  I appreciate it tremendously.

"to women it matters who the person is unlike us guys !"

Not true. Depends on the lady. I for one do not need to get to know a woman before enjoying her body. Too each her own.

In the case of the OP I would recommend it since she doesn't seem completely sold on the idea.