Need harness for 75 Trans Am running GTO interior/speedo

[qnitro]

OK, Im looking to build the harness.. anyone have any experience or know of a company who can help with building a custom harness?? Im running a Fast TB and need to build out a harness that can run this with a Factory ECU and be able to run the factory speedo.. Any hints?? I have reached out to speartech already waiting on there response...Im planning on asking vintage air to monify the factory GTO A/C control to make it work( they have done it before)

Here is the car https://www.pro-touring.com/showthread.php?85340-Trans-Am-Bandit-1975-to-1977

Thanks

Kevin