Headers only very slightly improve performance on a 216. There a book - How to Hop Up Chevrolet and GMC 6 Cylinder engines by Huntington Roger - that goes over all the various possible performance improvements for a 216 and 235.

On Barns and Noble:
http://search.barnesandnoble.com/oo...title=hop+up+chevy&ean=2802729921615

Your best bet is to update the intake to a 2bbl, 4bbl, or dual 1bbl carb(s).

For the cold concern, intake water heaters are available. http://www.stoveboltengineco.com and http://www.cliffordperformance.com sell parts.

Also, check www.inliners.org.


Jim