will hks skyline pump fit?

[BlitzBoy]

You will be fine on that pump

[BlitzBoy]

So with the standard wiring, what sort of voltage does the fuel pump usually get?

who knows as most peoples wiring is 15 years old on a FD, some have seen as little as 8 volts (which will give very poor flow) some see the normal 12. with rewire mod you guaranteed almost 13 volts and hence more flow

[jammy_uv]

for better voltage get a sard Fuel pump relay kit - or i think the MSD voltage booster might do - never used the msd myself but i am using the sard voltage booster and pip has said its worth it.

secondly get good grounding kit - always helps in general and its cheap.
reliability mods are vital.