I'm looking for information on what I need to do to select the proper headers for my 66 f250 custom cab / camper special

Specs:
Engine: 69 F250 390. 10.1 comp
Bored .060
Block Squared
Crank ground .030 back to round
Rotating assembly balanced
D2 Heads (completly rebuilt with hardened seats) also had them milled
Heads ported Ported
Edelbrock 1406 4bbl carb
RV CAM
Allum rocker arm end supports (broke 2 rocker arm assemblys on the original 352)
Double roller Timing gear and chain
High volume oil pump
Started using Schafer Oil after seeing a demo where I work.

It also has a NP435 Transmission and a Dana 60 4.10 diff. Also upgraded to electronic ignition.
Trying to get the best fit for headers for the application.
Right now using dual exhaust with the stock manifolds and glass packs.

Not sure what size headers to really go after shorty or long tube. What pipe size will work the best.

What issues should I look out for when putting the headers in. Distance between pipes and starter, clutch linkage, etc...??

Would welding a custom set work better than a pre made set? I am not the greatest welder but I feel comfortable taking on that challenge. I have a craftsman 110V MIG Flux core wire feed welder I use for body work.

Would tuning the exhaust be of value to take into consideration.

I'm planning on putting a butterfly valve in to change between open headers and glass packs. Unless it will have too little impact on performance.

Anything else important to know about headers to get the best bang for the buck. I spent a little over a year doing the engine and trying to understand the science of what I was doing to not just throw a hodgepodge engine together.

Sorry lots of questions but I want to do it right the first time so to me planning is key to doing just that.

Thanks,

 

Have you checked Summit to see what they carry for your truck? If it came with a 390 there are probably several options.