H2 Rims On My 1990 Sierra 2500? Will They Fit?

[blitzor]

Hi everyone... I have the chance to buy some 17" H2 Hummer rims with the 8 x 6.5 bolt pattern that my 1990 Sierra 2500 has. The problem is that my stock rims/tires are 16" and have 245 75 R16's and the H2's are 315 70 R17's. I'm not sure what problems I might encounter, but the fellow selling them said I might need a body lift kit of 2-3" and they cost less that $200 for the kit... can anyone out there make any suggestions, recommendations, or may have even tried something like this before? Thanks.