Eaton 8 lug rear question and will these tires fit?

[TwoFiftyShifter]

Couple questions about a 1970 3/4 ton 4x4.

1. Are brake parts hard to find for the Eaton HO rear axle? I'm considering starting a K20 project and before it heads down the road it will need a brake overhaul like master cylinder wheel cylinders, shoes and so on. Are these tough to get like some have said on here?

2. Would 255/85R16s on 16x7 Ford steelies fit on this truck without a lift? Truck has HD leafs from factory but are probably a bit worn. It will only see light off roading like fire roads and Jeep trails. No rock crawls.