How does the surge tank work?
Also how would turbo work on this setup?
Even though the injector is further from valve, it should still be better than with carb.

Read up on it in Datsun1200.com Tech: EFI and Tech: Turbosupercharging

I went through it, but im still unsure what the surge tank does? Is it used to collect excess fuel going to injectors, then returning it to fuel tank?

When you go around corners and the fuel tank is low on petrol, it may suck air for a second. This doesn't bother a carburetor because it has a fuel bowl that it draws from. But EFI will stall if the fuel flow stops for a second.

So you have to prevent this problem. Modern cars with EFI have a fully baffled fuel tank with special fitment of submerged fuel pump. Older cars don't. So you can either swap the fuel tank, or you can add a small tank thats always full and has the EFI pump connected to that. The small tank is kept full by a low pressure pump, such as the the stock A12 pump. The main EFI pump is usually medium pressure, say 20 to 40 psi. It's called 'anti-swirl tank' because the fuel won't swirl/slosh to one side, away the fuel pump.

Or you could just keep the fuel tank at least half-full.

Thanx, that explains a lot!