With the keyboard, it should be relatively easy (that is, compared to your other options) to gut them both and put the bluetooth pieces back into the G3 keyboard. With the mouse, on the other hand, you're probably a bit more limited.
I'm going to assume you're taking about the Apple Pro Mouse instead of the Apple USB Mouse (hockey puck), since nobody would want the latter. I'd really recommend picking up an "Apple Wireless Mouse", later known as the Mighty Mouse, I believe. It's the Apple Pro Mouse's direct successor, basically the same form factor with wireless innards. A very quick Googling looks like you're going to be eat a $125 bill for that, which leads me to suggest a Magic Mouse.