A good block to start with would be a 1 pc rear main factory roller block. Vortecs are a nice factory head but require some work to get more than around .470 lift or so.
Read through these links for good vortec info http://www.crankshaftcoalition.com/w..._cylinder_head
Vortec Cylinder Heads: The Definitive Guide - NastyZ28.com
Use Google to search for 383 builds. There are so many out there you could not read them all in your lifetime.