.

 

you'll be money ahead buying the 1 5/8 headers. I wouldn't even consider anything bigger for your application. Unless you are going big hp in the furture than you might want to buy once instead of twice. But you should be fine with what you are planning. The only choice would be single or dual exhaust. You could go either way and make the same power. One you will not have clearance issues the other way you might have slight issues.

 

Here is a header chart size I copied from one of David Vizard's articles. It is base on the exhaust flow numbers of your head. Hmmmmm. Site won't let me upload the chart. If you can find the exhaust article by David Vizard it has some very good information.