If you have spool mounts then loosening the bolts that go through them will let it tip more.
If you have wafer mounts then loosen the mount to K frame bolts.
That should give you enough.
I don't know what kind of mounts I have but I do know I have an all original '69 Barracuda with the factory 318/904, A/C, PS, PB.
Today I will loosen the mounts and try again!!