Clarksdale, MS--the golden buckle on the cotton belt
Proud Birdie is the sire of Alota Gator Bait who stands as a sport horse TB stallion in Ohio and seems to be used a good bit for Appendix QHs.
Suave Prospect is the sire of Suave Jazz, who is one of the horses in the current RRTP 100 day challenge. Maribeau is the full brother of Queen Sucree, the dam of Cannonade by Bold Bidder, who won the KY Derby (as did Proud Clarion and Lucky Debonair, IIRC) and is tail male in at least one Olympic eventer's pedigree--French, Athens 2004, but the name escapes me. A bit too much ND and Native Dancer for my personal tastes, but the pedigree is very nice. There are a number of videos of Suave Jazz on the Retired Racehorse Retraining Project website. Proud Clarion is pure Galbreath breeding, a tremendous virtue where sport horses are concerned (IMO).
The double to Lucky Debonair on top is excellent; and he's free of both NDs.
Bolero was an excellent line for TB showjumpers back in the day.
You have the Rasmussen Factor (which has been well debunked) through Cosmah and Natalma.
Tail female is 4-m, which is one of the lines that came from an English import in the late 1700's--early 1800's--Magnolia. It existed only in North America for a couple of hundred years, then got exported back across the pond. Very accomplished American line.
Horse is bred for classic distance, not sprints. She, is, however, not bred particularly for durability if the NDs and Unbreakable are all added up.
"I'm a lumberjack, and I'm okay." Thread killer Extraordinaire
You have a double to Mr. P top and bottom and add another line on top to Northern Dancer. That means two more lines to Native Dancer.
Nobody in racing seems to have done anything close to this cross. I checked all the available options on equineline for the nick and came up with 0 foals for all the crosses. Both Danzig and Fortunate Prospect had over 1000 foals.
Frankel and his three quarter brother Bullet Train are bred with Northern Dancer lines on top of Northern Dancer lines. It appears this is a strategy used often in racing. Also, Norther Dancer over Mr Prospector and Northern Dancer over Roberto lines. Of course none of these are like what you're trying to do because you have double Northern Dancer and double Mr P. on the top and bottom. Regardless, because the lines to Native Dancer are in the sixth generation it's not likely his influence will be great. (I did have a horse who had all of Native Dancer's unsoundnesses, but he had Native Dancer in the third and fourth generations, through Northern Dancer and Restless Native, each in the second generation.)
So from my very unsophistocated and self taught perspective you're breeding a racehorse to the second power