I bought a megasquirt-2 for the 440 I'm building right now. I bought it before ms-3 came out. You can buy a generic, premade megasquirt engine wiring harness for about $60. I did anyway, bought it from diyautotune.com, the generic harness comes with wires of all different colors, they are labeled and you need to crimp on your own sensor connectors. But at least I don't have to make the whole harness from scratch. MS-2 will do everything MS-3 does, except MS-2 is batch fire only, not sequential. I don't think it's that big of a deal, some guys do. It's still a huge upgrade over carb and better than tbi. Batch fire is what the oem port efi systems were in the 80's for the most part. I think I paid $60 for the engine harness and $250 for the ms-2 unit, however I did have to solder it together myself. MS-2 was primarily designed to use MAP or Alpha-N for calculating fueling but is also able to use a MAF sensor should you wish to go that route instead.