Mike, headers should be your last worry.....there are tons of header kits out there.....you just piece them together and weld them up. Custom headers.
I'm running Vic Jr cylinder heads. I ordered them bare and assembled them with the correct valve springs, shims, retainers, etc. Also, I don't know if this is true for all Edelbrock heads, but the ones I have seen don't have spring cups on them....so I put those on as well.
I'm using a Comp Cams hydraulic roller cam....230 degree duration, .544 lift, 110 lobe separation. I should have went with the biggest roller cam they make.....Desktop Dyno estimated a 57 hp increase with my heads and intake. I have a lot of faith in DD...it was only 2 hp off from the actual dyno results.
Also, from my research in dynamic compression ratios, I could have went another half point in compression with my cam selection.....could have went 11:1 and still run on 93....
Like I said before, don't settle.
If they can put a small block Ford in a Sunbeam Tiger, you can put a Windsor block in that Sprint.