Lowering 85 Sierra on 26s! few questions?

[jeepc1026]

Yo whats up ladies and gents. new to the site need get a few answers for a few question? i have an 85 sierra swb just picked it up i have some 26*10s i want to throw on it with a western chassis 2 1/2 and 4" drop will 305-30-26s clear the drop? and also what rear chrome bumpers of other gm trucks interchange or fit wit slight modification? (i like the 67s 68s chrome rear bumpers the smooth looking one) any tips or opinions or comments or knowldge are welcome thanks guys