Install new cab mounts - 67 K-20 fleetside

[marina blue bob]

any advice from those who've installed new cab mounts ? Is is just a matter of putting 4x4's under the reinforced floor channels and jacking up the cab carefully ?

also, after putting in new cab mounts, can I expect the lower belt line of the bed to no longer line up with the cab ?

Thanks for any advice out there.