That is a very good question, and shows rare perception.
Although Volvo resistance wires may vary by only four inches, on domestic V-8 engines the variation may be as much as 10 or 12 inches. What is important is that a threshold resistance is achieved that results in an adequate firing voltage for the shortest plug wire. Beyond that length given good primary performance, the firing voltage is essentially similar. It is helpful to observe an old time ignition oscilloscope in action to see the effect of increasing resistance.
In the sixties Bosch used copper core wires, and used a pellet resistor in the plug connector, and sometimes another in the distributor cap connector, to ensure equal resistance on all plugs leads.

Resistence is directly proportional to the length of wire and its diameter. A nice new set of Bougicourd wires (OEM) for your brick will have a difference of like four inches between the longest (for cylinder number Four) and the shortest (for cyl #1 i think). Anyhow the difference of four inches is negliglble. Resistence for you wires is measured in the thousands of ohms thats a lot to make a few inches amount to any difference. Wish my wife saw it that way...

hmmmmm
probably should.

They aren't on my 88 (and the original ones on there were marked 'Volvo').

-b.