then you'll need 2 3/4 inch threaded pvc fittings 2 3/4 to 1/2 reducers, a short piece of 3/4 pvc pipe 2 5/8 barbs with 3/4 male npt threads.
in the end you're probably gonna spend about the same or more and have several joints for potential leaks. pluss the space these contraptions will take up.
some times doing things the right way first is the cheaper option.