That would be a mammoth task indeed. Not just the engine but instruments, wiring looms fuel tank and all the extra fuel parts for the diesel, then there is the heating in the cabin to consider with the possible need for an electric aux heater. Then there is the suspension considerations, the battery, the drive shafts etc.
You may be better looking for someone who has a really nice diesel but now wants a petrol due to ULEZ and working out a deal with them.