Return line back to the filter.......
On our engine, we installed a CAV filter similar the that Racor mentioned by Butch and mounted in the same place as on a Dursley Lister. The injector overflow is routed back to a tee just ahead of the filter inlet. The engine is using a genuine Lister fuel tank with the float and sloped bottom. The tank has a fitting near the top for fuel return, but we're not using it. The only reason for routing the overflow to the filter is that it's closer than the tank. Seems to work OK. I suppose if the return line broke, it would empty the tank.
Otherwise......
Cheers
Hugh