welcome to AZ, good to see more south ozzies' on here... don't mind the ham lovers.
the oil leaks are possibly from either the front crankshaft seal, sump gasket, rear main seal or the O ring that seals the distributor housing.
as for engine conversions, the sky is the limit... but i'd look as doing a G16B EFI swap, pull the old engine & gearbox out & put a clutch kit & new clutch cable while it's out.
the best option would be to pick up a EFI SWB Vitara wreck or a complete one with good running gear & a stuffed body as you'll need things like the wiring loom & EFI fuel tank etc.