headers with a 3spd

[cadiman67]

i've been searching the forum for this answer, and can't find it.
i have a 67 c10 swb fleetside, originally a 6cyl w/ a 3spd on the column, it is now a 327 and has been converted to a floor shift, i would like to install a magnaflow exhaust system and want to know what headers would work with the least modification, i would prefer long tube, but whatever works.
someone here in town has a set of flowtechs that are supposed to fit this truck, but he doesn't know the model #
i just found this forum today, and i haven't been able to stop reading it yet.
i'll post pics of the truck as soon as i can.