Yeah, when I was putting together my ERA I thought about a new block, but went with an old one because it can give you a leg-up in a lot of states. This is kind of interesting:
Kit type cars will be designated by the year of the engine and are required to have an emissions test based upon that engine year.
Source: Division of Air Resources, NEW YORK VEHICLE INSPECTION PROGRAM (NYVIP)
http://www.dec.ny.gov/docs/air_pdf/vipsiprev.pdf