Not much information is available about the true Nebraskan, but I will add anything I can find here:
This is a .pdf of an article from 1950 found by Kevin Porter. Courtesy of Turkey World Magazine.
Origin: America
Classification: Heavy
A pied colour mutation produced by a non sex-linked recessive gene, which appeared in 1947 in a closed flock of Broad Breasted Bronze. Thirteen poults were hatched the first year and these formed the basis of a new true-breeding variety named Nebraskan by the originator R.H.Jandebeur of North Platte, Nebraska.
Colour: male
Head: Red, changeable to bluish white.
Beak: Horn
Eyes: Bluish pearl
Throat-wattle: Red, changeable to bluish white
Neck: White, with surface speckling.
Back: White with flecking of black, red or blue. The saddle has most abundant flecking.
Tail: main tail: mostly white with flecking towards the tip. Coverts and lesser coverts, mostly white.
Wings: White
Breast: White with speckling.
Body and Fluff: Mainly white with some light flecking.
Colour selection should be toward the lighter-coloured specimens which show a fairly uniform, lightly stippled pattern with white undercolour everywhere and without conspicuous dark coloured areas anywhere.
Legs and Feet: lower thighs white. Shanks and toes – salmon.
Undercolour is white in all sections except the back where it may be slate-coloured.
Female
Similar to that of the male but has less heavy flecking.
Standard Weights
Mature stag 13.60 – 18.14kgs (30-40lbs)
Young stag 11.33 – 15.87kgs (25 – 35lbs)
Mature hen 8.16 -11.79kgs (18 – 26lbs)
Young hen 6.35 – 9.97kgs (14 – 22lb)
Defects
Flecking sufficiently heavy to mask white. Any additional colouring.
Day-old poults
Creamy white with a tan or grey blotch on the back of the head.