Where to get 273 Head Gaskets?

I'm in the midst of finding parts for my 273 build. I ran into the same problem.
The 273's small bore needs a small gasket. A 4 1/8" head gasket seems too be too big to keep the compression of the Hypo 273's where it should be. The heart shaped chambers of the 273 head are oddly shaped and not symmetrical
on the arc side. A 4" diameter gasket looks like it would work best but I haven't finished checkin' things out. I do have a set of 302's that I can compare with.
toolmanmike