Originally Posted by cdminter59
If they are the Patriot Freedom heads 2168 with the 185cc runners they should work real well with your 355 motor. The 64cc chambers with the flat top pistons will have about 10:1 compression which is good for aluminum. I would be worried about detonation with the iron heads especially after being milled. Be sure to have the matching valve springs for your camshaft installed on the new heads.
I knew I would get some great opinions but never thought they would come this fast. Thank ya'll so much. I was kinda worried about detonation when I first put the heads on but I took a chance and am running my timing a little lower than I normally do and also raised my octane level to 102. I think I'm gonna pull the heads and go with the Patriots, which are the 64cc. 185cc., and run a set of "462" on my 400. If I found a pair of good Vortec heads, would I have to drill the steam holes in them to run em on my 400?