Probably a Carter 4070
https://www.nzperformance.co.nz/carter-4070-72gph-6psi-fuel-pump
I run one directly to the carb - no regulator - on the Mercury and it seems OK. I do have it mounted at the back of the car down by the gas tank.
I had trouble getting my 'new' VN engine running after installing it. I think the main issue was injectors that were stuck. On the 3.8 it's possible to remove the raid and injectors as a unit and let them spray into the air. Not sure if this is possible on the V8.
You can get new SU carbs from Burlen in the UK. E.g.
http://sucarb.co.uk/conversion-replacement-sets/metro/hif44-service-replacement-carburettor-for-a-austin-metro-1300-1980-onwards.html
Sure.
No cert required for that, see Table 7-1-1
https://vehicleinspection.nzta.govt.nz/virms/in-service-wof-and-cof/general/vehicle-interior/seats-and-seat-anchorages