I have looked at a couple of Belvedere/Sat 65's lately, and they have both had 318 poly engines. I see that Schumacher has swap mounts to put a 440 in on the stock k-member. The stock k-member brackets look taller on the poly and it got me to thinking about headers for this combo. What all is involved with the swap and who makes headers to fit, and are there any other pitfalls to doing this swap? Thanks, Lee.

there are only a couple of headers that fit. TTI is one and can't remember the other.
Some people swap out to a 66 and up kframe so they can use any headers, but that causes its own problems.

This may help. We covered it here: 64 - 440 Swap

Thanks!

Schumacher's conversion mounts work fine. I run a Max Wedge exhaust system on my car, so I don't know about headers, but a lot of guys run headers, so something must work.
The other issues could be: auto trans shifter, trans mount & crossmember modification, driveshaft & ft yoke, depending on the rest of your swap. I used a '69 RR 4-speed & rearend, stock trans mount, modified the trans crossmember, and had a driveshaft made when I did my '63 (poly stick car).