Building your own headers.

Rat Bastid said
Those will work.

Use slip on collectors.

When the headers are done, cut the flanges so each header is 3 pieces plus the collector. It‘s mush easier to install the header in pieces.

Primary tubes should be 28-32 inches.

Eventually when my tti headers aren't pretty & don't remind me of now being broke I'll probably do that 3 peice deal and get some or make some sweet merge collectors Depends on how much a pita it is how they are.