There's a bunch all over the place. Its actually very simple in your use case. The easiest way would be to call up one of the companies that does LS swap harnesses and tell them what you are doing. They can provide you a harness that would plug into the trans and have open wires to go to Power, ground, tach, and TPS.
You can get a TPS sensor kit to bolt to your Holley here:
https://www.innovatemotorsports.com...sor-tps-carburetor-applications-p-n-3930.html or use some other method.
You can also decide to modify a stock harness and use the info from various forums and websites like LT1swap.
https://www.lt1swap.com/wiringharness.htm
Its really not bad... if you got a computer and pigtails from somewhere(they were in almost all 99-2003 chevrolet vehicles and will have the blue and red connectors) then you can just get the trans harness section when you get the transmission and connect them up. I think the transmission harness will only have 3 connectors and maybe 6 wires? Plus 1 wire for the tach and three wires for the TPS. It also would give you the ability to control electric fans and also to read out data over an OBD2 interface such as trans temp, coolant temp, RPM, TPS, etc...