SBC heads/headers...edumacate me

[Lurch830]

I pulled the broken driver's side manifold off the C30 to find out the heads have a square port and I can only find round and oval port headers. I'm guessing if I can't find a square port that oval port would be 2nd best with round being the worst? How bad will the oval port headers restrict the exhaust? I'm guessing not much since this isn't a high-revving/performance motor, but while I'm throwing parts at it I'd like to get the best bang for my buck (hoping to only spend $100-$200). Any suggestions/links for a square port block hugger/shorty header in case my google-fu isn't working?

Thanks,
Brandon