Lockhart oil cooler

I have a 1977 KZ650C1 with a lockhart external cooler will it require more oil when I change it?

I guess if it's between the lines on the oil window it should be okay. I just changed it and added 3 quarts it looks like it has enough judging by the oil window lines.

No.. Just fill with the specified amount of oil as quoted in the manual.
However ! If your cooler has the hose fittings on the top of the cooler matrix it will hold a small amount of oil that will not drain back into the engine at rest and this will give the system a slightly larger oil carrying capacity.
If this is the case, once run and then left to settle overnight you can top up the oil in the engine back up to the upper sight glass mark to account for this.. Just remember to also drain the cooler of old oil at service time.