4.3 Voortec Fuel Injection Setup

I am installing a 2001 S-10 4.3 Vortec V6 with 4L60E trans in a 1965 Jaguar. Am converting the car to fuel injection setup. Have added hi-pressure elec. pump & am ready to run the fuel lines. There are 3 lines on my motor. I think one is supply, one is return to tank, the other is? How do I sort out which is what & hook them up?
Any help appreciated.

Welcome to AF
Your 4.3 engine has 2 fuel lines going into the top of it.
Large is the high pressure feed line.
The smaller one is the return line.
Where is the third line hooked to?
You will need a fuel pump that can supply 6o/66 lbs of fuel pressure.

Third line goes to some sort of valve located on the passenger side of engine directly between oil filler spout and fuel injection. Don't know purpose of the valve or line, but the line runs in tandem to the fuel lines.
Thanks for the tip on the pump - I was aware.
Cheers

Maybe the tank vent or vacuum line.

If made with the fuel lines it maybe small line or the vent hose on the truck fuel pump module.
MT

Do you know if the engine will run without that vent line hooked up?

Also- am installing a device that translates electronic sppedometer readings to manual so I can use my old speedometer. To calibrate it, I need to know the "number of teeth on the transmission exciter gear".
Chevy dealer parts guy is no help on this one. Any ideas on where I can find out?
Thanks

It should but would be better to have it hocked up right.
Pop the tail shaft and count them.