Raine, can't really help with specifics since haven't come across this condition but will just say that after just having no option but to have a puppy PTS there are no guarantees ..... even if you go for an 8 wk old health checked pup.
Have had lots of retired gundogs and yes as they get older or if they come with existing conditions there is commitment financially and timewise but also if you can see that dog suits you it will also bring much pleasure. We never know what's around the corner even with young, healthy looking dogs.
King sounds like a super dog. (Do have a soft spot for greyhounds
)
with making the right decision for you all.