I believe that you really need to investigate this with your home state or the state in which you want to register the car. I believe that some states only require that you bring the car upto the specs required for that model year. I think that it varies from state to state.
Like 5 years ago, I friend of mine brought in an Aston Martin Lagonda to the state of Florida and all he had to do was install emissions to be able to register the car. Additionally, back in the 80's a diplomat friend of mine parents, sold a benz that was completley european (sans emiisions) and when they sold it, the new owner just had to also have emmissions installed. But, I do not know how much that can cost?
Insanity: doing the same thing over and over again and expecting different results.
2006 - Suzuki Gran Vitara (2.0 L fully equipped) Like this car so far except for trying to put on the seatbelt.
1988 - 190e - 2.3L - 172K miles (It now belongs to the exwife)
1999 - Chevy Blazer LS Fully Equiped - killed it June 2006
2001 - Honda Civic EX - 68K miles (sold June 2004)
1963 - 220S - Dual Carb 6 cyl. (sold)
1994 - Yamaha WaveRaider (fun to ride)