Natural aspiration, or EFI???

[JT Ranch]

If I build a 1991 - 1998 4.0 with a 1979 4.2 crankshaft, would EFI be the best route for more power, or nat. asp.?

Also, I'm in California, the dreaded emissions state, and, I've heard that I have a better chance of passing emissions testing with EFI.

Thank you in advance for your thoughts!

[SkylinesSuck]

Naturally aspirated means no forced induction i.e. supercharger or turbocharger. EFI is electronic fuel injection.

I think you are asking EFI vs. carb, and while both can work and pass emissions just fine, EFI (especially with tuning) would have an advantage, along with drivability.

[Cheromaniac]

EFI wins hands down for drivability under all conditions, more power, better fuel economy, and lower exhaust emissions.
In your case the choice between EFI & carb is a no brainer.