With some extra pushing and stretching, or some extra tightening of a hose clamp, I wouldn’t sweat the difference between 3/4 and 5/8 on an exercise like you’re performing.
If given the choice, I would probably prefer to tighten a 3/4 hose on a 5/8 fitting, rather than stretch a 5/8 hose over a 3/4 fitting. But you will figure it out either way.
