Best donor for MPI

Goldduster is right, if you are planning to build an upgraded engine for your car, or even plan on using certain camshafts. It really depends on what you are planning for the car, a mild 5.9 with intake, and exhaust will be fine with factory stuff, but beyond that you will want to upgrade. The factory diagnostics do help a lot with daily drivers though. Also cost can be a factor to consider since you have all of the factory pieces. When I did my magnum swap it was similar to the stuff you had laying around, and with fuel system, oil pan, and misc stuff my total swap cost was around $400. I figured if I ever built a nicer engine (not likely for a c body sedan) I could upgrade as I went. I haven't priced megasquirt stuff, I think it's pretty reasonable, so it it a good option as well. It will be a cost on top of the other swap pieces though, so just think about what you want to do with the car an go from there.