Does anyone produce either stepped 1 5/8th to 1 3/4 headers, or simply just 1 3/4 inch headers for small block 72-80 D series 2wd pick-ups?

What are the fast small block D-series running for exhaust?

UPDATED below.

1979 Dodge Lil' Red Express - 360 rwhp, 13.2 @ 103mph
1968 Coronet: 318, 2.76, 15.2 @ 92mph! (SOLD)
1976 Valiant: 360, 3.90, 12.90 @ 106 (SOLD)
1989 Shelby CSX #500/500