I've decided to go electric so where is the best source to draw power from? I'll be using an oil pressure safety switch and also run the power through a toggle switch to activate the pump for priming the system on start up after the car has been sitting for long periods of time. This is a 67 B body with a stock wiring harness and fuse box.

Pump in the rear? Battery in the rear?

Use a relay. Run the relay with the switch. Run the high amp line from a good power source - direct from the battery if it is in the trunk. Wire size is dependent on the pump. If it needs to run from the front to the back of the car, it needs to go up a few sizes from what you think you need.

Switch/pump should only be hot in IGN ON, not constant. Pump should quit when the ignition is turned off.

Stock systems don't work well for adding stuff. The BAT+ stud on the starter relay is probably the safest source.

The pump will be near the stock tank, battery is up front. The pump is a small low amp setup, less than 10 amps. For sure on a switched "key on" source. I guess that is my main question is to where to draw the key on power source from. Without going directly from the positive side of the battery terminal what is the next best place to pull from?

Sorry, just read that last line, didnt scroll down far enough. Thanks for the response.

8 to 9 amps is still alot for the stock system in particular because the pump probably should be running during start and then of course in run.

If you really want to do this my suggestion is use a relay.
Trigger the relay with the ignition 1 (run) wire. Piggy back terminal at the ballast resistor is probably the best and will be reversible (no cutting needed).
Get power to the relay for the pump by connecting to the alternator output stud. Use a fuse on this line. Size the fuse for the pump or wire size, whichever is smaller.

Connecting at ignition 1 means power from ignition 2 (start) will trigger the relay on during starting. If the relay trigger demand is low (less than an amp) there will be very little drop in voltage though the ballast resistor.
Drawing power for the pump from the alternator means the ammeter will still read correctly and also avoids putting a constant current through that extra distance, extra connections, and the fusible link.

Think about a mercury switch to kill the power if the car stops upside-down etc.

On a side note, if you keep the mechanical fuel pump connected you will have 2 things going for you. 1. you won't need a fuel regulator and 2. the mech pump will still draw pump if the electric pump takes a dump.

OK, I see the point of the relay so now I am trying to understand where the oil pressure switch would wire into a relay setup. Would you happen to have a diagram? I'll assume the relay would physically be near the oil pressure switch somewhere on the firewall and not near the fuel pump. After looking into the relay more it looks like a relay kit from Ron Francis would simplify this quite a bit. I'm still not finding much on where in the circuit the dash toggle switch would go.

toggle switch to oil pressure switch then to fuel pump relay trigger terminal

Personally, I like the relay close to whatever it is powering. Makes troubleshooting a bunch easier. All you need is the trigger wire and a fused power wire to the rear of car. Pretty simple to do.

Somehow I missed request for toggle switch and oil pressure switch. Just saw the stock wiring.

Suppose you could piggyback onto the 'always hot' buss in the fusebox. If there is an empty tab on the buss, remember this is unfused.
Run that wire to your toggle switch with a small inline fuse. Then toggle switch out to pressure switch, out of switch to relay, out of relay to ground. That could be 16 or 18 ga
Personally I'd keep the wirelengths short as possible and look for a spot to place the relay fairly central to the four wires connecting to it.

Only time a carb bowl should be a little low in fuel is first start of the day, week, etc.
Next time you drain fuel from a bowl into tin, set it on the work bench and see how much is there the next day.
The main thing that dries out is the intake manifold.

Maybe this will help you as it helped me. I saw the article sometime in the '90s, I think this is rehash, but whatever....

https://www.hotrod.com/articles/safe-and-efficient-electric-fuel-pump-wiring/

This plan has worked for me for alot of years, it's cool but it is lacking one thing--A way to manually fill bowls when they are empty.
Using this setup the pump will kick on when oil pressure is developed during cranking, but myself I like to have the bowls
already full before then. So I changed it a little bit to allow me to do that easily from underhood, which is handy when making
changes to the carb that require the bowl to be pulled, or if it has sat for a long time.

Put a second toggle/momentary switch in that jumps the pressure switch.

I do that with my pressure cutoff switches for ignition. flip a switch to get it hot when starting, flip it off once running. Same approach here.

So it looks like the only way to run this how I would like is to have 2 toggle switches as stated using a relay. I also had another opinion from someone who thinks I am way overthinking this whole thing with only wanting to use the electric pump for priming the carb after months of sitting and a few times a year with some spirited driving or a pass or two at the strip. I really have no intention of running the electric pump 98% of the time for normal driving.

Thanks for that link Zippy and appreciate the help from the others.

If it's not going to be running as the main feed pump, direct wire a relay on a toggle. Done.

Flip switch, prime bowls, shut it off.

The pressure switch is only good for a continuous use deal. Don't need it for priming only.

Stick with the simple solution.