He won't have a 'breed' in 20 years, not with so many breeds added to the mix. Victorian gentlemen achieved such things in their own lifetimes by having huge resources, kennels, stables and tenant farmers to rear and walk pups/dogs. It's very hard/virtually impossible for one man to do in the 21st century.
I thought it generally takes about 8 gens to get the breed/line breeding true.
In russia they done a study and were breeding domesticated foxes after 8 gens, sure it was something similar for the Korthrans Griffon too
But for that to happen u have to start out with a very clear plan of wot ur looking for, and back in the old days anything not meeting the standard would go for a swimming lesson inside a sack with a brick for company, (wrong colour, poor temperment, too small/large, poor scenting etc = swimming lessons.
As kieth said very few have the size of kennels to do it nowadays or the will to sterilise or PTS any animal not up to standard.
Just look at his photo 2 out of the 4 look similar other 2 completley different looking 1 just looks like a springer.
To be honest i can't even see the logic of crossing the 2 breeds, ( i get the idea with lab/ess or lab/gwp, generally to make the lab hunt a bit harder and calm the harder hunting breed down a bit) but a springer to a pointer ur only going to end up with a dog that ranges too far to shoot over and to near to be a true HPR, if ur dog even holds a point, most likely just going to be a fast healthy fairly wild dog
If u want a slower shorter ranging pointer there already is breeds like the brittany spaniel or spinone or bracco