Thanks for all the info everyone! Here's where I ended up...
I bought the last two Aussiespeed big-bore cylinder head gaskets (AS0193) in the US (sorry folks) which come in at 0.055" compressed; leaving a confirmable safety margin. The pistons do have reliefs for the oversized (Ford 289) valves, and with .476"/.479" valve-lift - I think I'm all set. Final compression here BTW, is 9.8.
Much appreciate all the shared knowledge!!
