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.