DSE Mini tub kit questions for 68 camaro

[68GCamaro]

Ive just got a few quick questions about the DSE mini tub kit.

1. Is it necessary to narrow the rearend to get the full backspacing allowed by the kit? If it does, how much does it need to be narrowed on with a 68 camaro 12 bolt?

2. Does the gas tank absolutely need to be narrowed? I'm on a really tight budget, so anything I absolutely don't need would help. If the gas tank needs to be narrowed what are the dimensions on it? Again it would be a 67-69 Gas tank.

I may have forgot a few questions, but I'll ask them at a later time if I remember them.

Thanks for your time and help!