Whenever we do such swaps we calculate the flat space on tank. Measure the diameter and then compare with the fuel assy available. Usually Toyota indus Corrolla fuel assy comes with a 5-6inch dia and any metal press guy can make a 16 gauge circular sheet with 3inch dia and you buy that fuel assy with rubber seal on it.
Then that circular plate is welded on to the tank, with calculation of pump height. Then it is painted and installed back with insulated wiring and it works well.
For Islamabad you can visit us for this job if you are unable to do this yourself.