Depends on how far the pistons end up down in the hole at TDC. And the final CC of the cylinder heads after valve job and milling. Average numbers show it at 9 to 1. http://www.wallaceracing.com/cr_test2.php
Bull Nose Formula/ 461/ Q-Jet/ TH400/ 3.08 8.5 / R44TS.
With a typical flat-top piston, a 98 CC chamber will yield right at 9.3:1 with a .040" gasket (actually 1 mm, but I won't quiblle over a couple tenths of a thousandth in the head gasket). and .010" deck clearance. Makes a nice, pump-gas friendly (92 or 93) setup you can make some serious power with, depending on just how "far" you take everything else.
6X-4 heads are popular among some on the 460-ish engines. I prefer the larger chamber. No need to push limits unless you're racing in a specific class where every inch-ounce "counts".