There's 2 different versions of the "245" port. a Std 245, & a Raised Port 245.... the RP head is identical in every way except they take about .250" out of the roof of the port. I would'nt use the RP on a 408, unless it was a methanol engine.

Both are designed to be ran with 2.14 or 2.15 valves.

The RP port can only be put into newer raised valve cover rail castings.

I posted Dyno #'s off a 245 non RP head motor that was hampered by a 2.1 valve (was forced into running this) about a month ago. Those were out of box untouched heads except a VJ. There is more flow to be found with a little hand work, but you can make substantial power with their OOB ports.

I've now gotten to see several sets of ICH CNC heads off of running engines & the chamber burn pattern is exceptional on them. Many complain about how BIG the CNC chamber is, but I'll take killer burn every time over a head with smaller less efficient chamber.