  The quality of a superconductor-normal metal-superconductor Josephson
junction (JJ) depends crucially on the transparency of the
superconductor-normal metal (S/N) interface. We demonstrate a technique for
fabricating planar JJs with perfect S/N interfaces. The technique utilizes a
strong inverse proximity effect discovered in Al/V$_5$S$_8$ bilayers, by which
the Al layer is driven into the resistive state. The highly transparent S/N
homointerface and the peculiar normal metal enable the flow of Josephson
supercurrent across a 2.9 $\mu$m long weak link. Moreover, our JJ exhibits a
giant critical current and a large product of the critical current and the
normal state resistance.
