Just did mine and had they same concerns Sprayed with wd-40 several times over a few weeks. I put a closed end wrench on them and tapped with a hammer to jar them, and to my surprise they ALL came out easy. The replacements from jbg are nice, but 4 of the long bolts bottomed before tightening. Good thing I have a huge selection of bolts.
Once a had a ford 390 with cracked exhaust manifolds and I was told by a ford expert not to touch them as he was sure they would break. That must not apply to the sbf. Good luck