Battery issue

[tagusloki]

I own an '86 Camaro V6 and am having problems with the battery hookup. The car didn't have a battery or terminals for a while and I'm starting to hook them all back up.
I'm 99% sure I have the correct battery (75) and 99% sure I have the proper wire hook up. If I put one terminal on I have no problems, if I try and hook up the other (either positive or negative) it sparks ridiculously much and refuses to hook up. If I try and force it it'll fry the wires.
I've checked the ignition to make sure it's off and beyond that the only thing I can think of it is manually pulling one wire at a time from either side and switching it over until I've tested every combonation.
Is there something I'm just missing from this picture? Thanks.

Edit: Someone suggested it could be one of the positive wires grounding itself, is that plausible? If so, how?

[wrightz28]

The negative is grouded to the block, the positive you can trace to the starter to know which one's which.

[tagusloki]

Right, I'm just wondering if one of the wires were improperly grounded would that be causing the issue?