I ran 10.9 C&B's in a Spica head with stock springs and no head modifications.
I use a large Zip tie with a thickness of .050" to check intake valve to piston clearance and two if them tied together to check the exhaust. Your clearance will depend upon cam timing. You should be able to use 101 LC on the intake and you may be able to get away with 98. That is when checking the clearance is important.
85 GTV6 3L
76 Suzuki GT500
2011 Jaguar XKR
A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke