There is a kit for that.
https://www.lilypadspeedshop.nl/a-85...nator-bracket/
1949-53 DRIVER SIDE FLATHEAD ALTERNATOR BRACKET
You`ve got your Flathead topped with a row of Strombergs on an Offy intake, but now you have no room for an alternator! This bracket kit can help solve that problem by mounting the alternator on the driver`s side of the engine.