You are replacing this:
$99.00 MSRelay-C: Assembled relay board
$85.00 MSRelayCable: Megasquirt to relay board cable
$46.00 LG-Wirebund: 10' wire bundle for relay board to engine
With this:
$79 harness.
https://www.diyautotune.com/product/10-39-megasquirt-wiring-harness-ms1-ms2-ms3-ready/If you are willing to junkyard it some, the sensors and pigtails are easy easy to find off any GM vehicle. The only one you really should consider is the intake air temperature sensor so it can pull timing if intake air temps start climbing as well. For spark only, you really don't need a coolant temp sensor (nor a TPS sensor). Again, it'll control timing and provide datalogging of your boost, rpm, O2 sensor (if you have one?) and if you ever decide to go TBI or such it'll run that too. Spending your money, getting an assembled 3.0 or 3.57 board, MS1, would be the way I'd go. You can always upgrade the processor on it to a MS2 or MS3 down the road if you get the bug.
