I don't feed them differently if they are heritage.
For hens, I want to keep the most mature by 24 weeks. Full adult plumage, starting to broaden out, and chosen for size and conformation. Color is a factor if breeding to standards.
For toms, they don't hit their prime until a year or more. But toms contribute mainly color, so choose the one with good size and conformation, and select based on purity of pattern.
I always try to keep a trio at a minimum. 1:1 tom to hen is really hard on the hen. 6:1 to 10:1 is easier on the girls. And if a single hen dies, it's hard to find another good one in spring when you need it. Toms are easier to find when they go hormonal/stupid in spring, so watch temperaments.
Royal Palms are lovely, but don't yield much meat.