You can run it like that but it isnt ideal, you’ll be adding a good amount of advance and skewing your transfer pressure curve from where it’s calibrated at, but it won’t break the pump. I’ve put 80 psi in front of a stock pump testing on the shop truck a few engines ago and it didn’t hurt anything, it kept the advance piston pushed all the way over all the time so it was pretty much like driving a pump with locked timing.
The 105p should come with a bypass regulator, it can cut your pressure down until you can get a good Holley one, they just don’t maintain pressure and adjust nearly as nicely as the real Holley regs but they will work for you. If for some reason yours didn’t come with one I can send you one of the mg regs that I never used.