Shafiroff is offering now 9.8 598cid engine:
http://www.shafiroff.com/pro/598_1065.asp
My friends 600cid (4.610x4.500) has 6.385 rods, that's 1.42:1 rod ratio. Not that bad as it first sounds when many 632's have even little worse rod ratio (4.75 stroke, 6.700rod = 1.41:1).