looking for ideas
 

I got a 406 and want to add additional cooling to the simesed cylinders.
I have a pipe plug inbetween the 3&5 and 4&6 cylinders on the head .
now where do i tap coolant off the pump?
Ive seen cars in the past with a 406 that had the extra coolant lines plumbed to the heads in that location but cant recall where they got the source from.

Some heads came with a coolant hole dead center of the intake flange (sounds like your heads), you can also get intakes (Super Victors for one) with coolant ports on all 4 corners. On my dragster I pump water in the front and exit out the back two ports on the intake. The coolant lines get plumbed from those center ports to a block at the tstat housing as a return, not pumping pressure into it.