You will have to bring in the vehicle under a bond (150 percent of the dutieable value) and sign a contract with a registered importer. This starts at 6,000 usd and up. However prior to all this, the EPA and NHSTA needs to be petitioned to allow the vehicle to be converted by a commercial importer. You can only make petitions for a few cases, one being a like vehicle was already manufactured to meet US specs. After all this paperwork is done, the registered importer has 4 months to complete the modifications, and submit the paperwork of compliance to the governmental authorities. If it takes to long, the govt can keep the bond, and seize your car and send it back to where it came from, or have it destroyed. You can see if there is a petition on file for your vehicle you want to bring in by visiting the NHTSA or customs website. The EPA certificate of conformity costs $25,000 usd per "Class" of vehcile/engine combo, and fees for the conversion by a registered importer start at 6,000 usd and go up to an unlimited amount. If the vehicle has never been privately imported then your looking at a very costly process.
Your also looking at a costly process to get the vehicle into Canada, as they have similar restrictions pertaining to private party imports. The big difference is in the US vehicle restrictions for vehicles over 25 years old, and Canada it's 15 years.