Well, I've never seen the FBI or CIA out enforcing the Clean Air Act. Emissions enforcement has been left to the individual states to police. So it depends. Do they do emissions testing in Houston? And if so, are they just worried about the sniffer or do they mandate that it must passa visual. Michigan never worried about the visual as long as it passed the sniffer.

As for an engine, how much were you going to invest in your 400? The ZZ4 GM crate motor can be had for around $3500 at your local GM dealer, can be made smog legal, and comes with a 2/24 warranty. Did I mention the 355 HP? Just something to think about.