I am really want to replace the sweep dash in my 71. I bought a used tach cluster and a perfect uncut wiring harness.

NPD says that for A/C cars (like mine) there are differences in the forward lamp/underhood harness.

Do I have to buy one of these or is it something simple that I can use the harness from a sweep dash?

Also how difficult is this conversion and what is a good average for completion time?

There is no differences between A/C and non A/C in the under hood harnesses. The forward lamp harness needs two wires to make the amp gauge work. The gauge/tach dash harness will work with either A/C or non A/C. Just make sure the harness is 70 or 71, 72 will not work for 70-71 cars without modifications to the bulkhead connector.

You should be able to complete the swap in one day.

I made sure the gauges and harness were both from a 71 before buying.

I was just concerned about the connections on the inside and outside blocks being fine, if my malibu underhood wiring works thats another $150 this site has saved me since yesterday (i was advised against a MSD ign box) :D

Considering its time for new 295/50 BFG at 100 bucks each, this is good news