Bummer to hear. Possible the engine was run low on oil sometime in the past maybe?
Do you have any pictures? Cross fingers that the bore in the cylinder head where the vacuum pump pushrod goes through is not scored up. The pushrod can be replaced, and so can the cam and followers, easily enough. But if there is any issue with the condition of the aluminum head casting, that would be a different challenge.
Although -- even that would be pretty easily solvable by just eliminating the vacuum pump and using an external electric vacuum pump. Several folks have done that and it works just fine.
So, don't despair!
There are solutions to this kind of situation. But let us know if we can assist. Pictures would help us understand better what you are facing.