Header info????

[Kdickie]

I have a 1965 MERCURY[not Ford} Econoline Pick-up. It has a 302 , 9.5:1 compression, Genuine Shelby dual plane Alum intake, 600 DP holley, GT-40 Aluminum Y303 heads,1.6 Alum roller rockers,Crane geardriven cam , .488 lift, dual point, Alum HV water pump, melling HV oil pump, etc , & currently Mustang stock "shorty" headers, a C-6 & 3.50 -9" rear
I have a set of Hedman big tube , equal length headers wihich will NOT fit , as the tubes on cyl# 3 & 7 rise above an imaginary line drawn through the center of the exhaust ports & thus HIT the floor of the cab , on this WEIRD application!!!!
Does anyone know if there are any "equal length" , big tube headers, which do NOT use an upward bend in the tube to gain the equal length? Picture indicate that Mac's make an equal length header for the 302 which appears to sweep OUTward rather than upward. To make the most of the GT-40 heads , I need bigger tube headers, as currently,the ports & the tubes arent quite the same size.
I run the stock shorties into a set of flowmaster mufflers through really short 2.5" head pipes & then out into 4' boom tubes. This truck is very quick, as it only weighs 2800 lbs with a full tank , BUT!!! its only quick in a STRAIGHT line!!!! still 1965 steering tech , Not that good!!!
Does anyone know if there is such a thing as a BIG tube header which may fit this oddball setup??? I believe that Ford racing may make a big tube shorty , which would be a second choice.
All help is greatfully appreciated
R K Dickie