What size exhaust???

[sixD8]

I have a 68 C/10 that has a 350 out of a 72 C/20. It has dual exhaust. On the way home it whent from sounding great to what I can only think is a blown manifold. Has some squared looking headers. Then goes straight to the pipes the that have 3" built in "mufflers" but it is one piece of pipe from the headers back. Anyhow...I don't see or hear anything on the pipes...I'm pretty sure is the manifold.

What size headers do I need? I see SBC headers on craigslist..but don't know what I need. Any help would be greatly appreciated.

[kgt]

some 1 5/8 sized headers would be fine, install them and then have a exhaust shop hook it all up...