Standard headers will have a short life, the heat will tear them up.
Best to get a 4 bbl type intake, whichever suits your budget better. Clifford or Offenhauser.

New 292 3 bolt manifolds can be had on ebay. They are made for the agricultural applications. But still the same as the big trucks used.
http://www.ebay.com/itm/New-John-Deere-E...=item337a3940e2
compare it to this one at a higher price.

http://www.ebay.com/itm/250-4-1-292-GM-C...f437175&vxp=mtr

Inliner Member 1716
65 Chevelle Wagon and 41 Hudson Pickup
Information and parts www.12bolt.com