If guys are not familar w/Chevy inline 6 cyl heads they can port through into a water jacket. They need to know where & how much they can port.
Unless they sonic check how thick your casting is & the port walls, I sorta doubt they are willing to do that for you & not charge an arm & leg sort to speak.
I would take your cyl head to a shop that has done many 6 cyl Chevy heads.
Just my two cents on that thought.
MBHD
