I ended up emailing the guys at
www.windsorfox.com and they told me the ones they use on there conversions are JBA shorty headers, 14 gauge with a solid 3/8 flange. I think u can get them with different coatings...and they claim they do not see power loss due to using the shorties (their opinion). I figure there will be some, but for the ease of working on the car and better clearance it would prob be a good idea (IMO). They r expensive though, around 500.00, I think.
Ryan