Yeah I had fuel pump from an A15 that actually damaged the eccentric lobe of the cab because it was either too long or of a different angle [can't remember) so there are some subtle differences.

Going electric because the stock one has failed is a big move and a fair bit of hassle if you haven't done it before. Why don't you just buy second hand pump that works? Never had a fuel pump fail in any of my engines though, you sure it isn't a separate issue altogether? i.e Carb float needs adjustment?