I've done the speed density to mass air swap. It's easy and the biggest expense will be the ECU.
About halfway down is the Harness I used for about $40.
Grab a stock MAF or a 94-95 70mm MAF and adapter, find the proper intake duct tubing, and score an a9l or a9p depending on your trans and swap.
My car is near stock, and it made ZERO difference in how the engine ran or power. But, I have upgrades coming so I needed it. If you aren't doing major engine work anytime soon, just leave things alone