you SHOULD have a sump as almost all aftermarket external pumps dont like pulling fuel, they like pushing it.
ignition box SHOULD be used if you are building a higher performance than stock motor, it will like a better spark
the fuel lines SHOULD be replaced, as carbs like low pressure and high volume, which is not what the factory efi lines were designed for.
bottom line is you can 1/2 assed your way around the car, and cut corners to get it done cheaper, but its much easier to use your whole ass the first time, and no go chasing problems because you didnt do things right the first time.
if its worth doing, its worth doing right
So all you're saying is you SHOULD spend $1000 to change a bunch of parts becuase OVERKILL is necessary... Pass.
Just throwing a sump on a tank will work like garbage... no baffles etc. Can't go overkill on everything unless you have REALLY deep pockets becuase face it... there is almost ALWAYS a better part.
Stock lines, aftermarket RTR dizzy and an unsumped pan with a good external pump will be just fine in MOST applications. Especially for a street/strip car. To spend $350+ on a properly sumped tank for a street car is just a waste of $350. Another $300 on lines and fittings, $200 on pump and reg, and $500+ on dizzy and box.
My last coupe ran high 11's without all that junk. With built e7's, 130,000 mile bottom end, TFS1 cam, hurricane intake and holley carb. i drove the car daily for 2 years and never had a single problem with anything aside from a bad balancer and a grinding 2nd gear. Not bad for an old beat up street car.
Now if you are building a drag car with a big stroker 351 base that you plan to push over 500hp.. ya, then that stuff doesn't become overkill.
My current car is getting a 357w... guess to "wholeass" it I'd have to do an all aluminum 460w with a dry sump oiling system, Complete fuel system, etc etc etc $100k later. lol
You ARE right though. To go all in and build the fuel system to handle anything you MIGHT throw at the car in teh future, a good sumped pan, an ignition box, and aftermarket lines would be necessary. But to the OP wanting to swap EFI to carb with a holley blue pump.... he's either within the limits of the stock lines, ignition, and tank... or his Blue pump is going to be too small anyways.