G'day,
i'm guessing you've probably already gone with a solution for this, but to help you with feeling better about it, i recently sourced some hooker headers for a 302 with the gt40 aluminium x303 heads (the new crate engines from the states). took a lot of ringing around and eventually got onto someone at holley who assured me that the ones he offered wuld eb suitable. of course they weren't, and in the end, it would have been cheaper to custom build them from scratch rather than modify to suit the 65 coupe installation. Liverpool exhausts quoted me 1100 for a custom set of headers for my 73 coupe about a year ago. things wouldn't have changed too much i don't think.
regards,
Andrew Banks