Dylan
That's a nice freebie score there!! These old brown Filter Queen's are great vacuums....they may not have the world's greatest PN, but they do OK if you put the brushroll in the "worn" position, & they have good filtration, suction & power.
I wouldn't worry too much about the cord....unfortunately, unless you can find an old brown junker you can save the cord from, Filter Queen is discontinuing a LOT of the parts for the brown models

. And of course, if the cord is available as a new genuine part, it will be pricey knowing how Filter Queen is. Oh, and so you know, the original power cord was 2 PRONG, not 3 prong.
About the brown powerhead....with this brown Filter Queen with the "marble" applique on the tub, there was actually 2 lighted PN's during it's run....first was a brown one with the same "marble" applique on top, & then they replaced that finish by making it's cover with a silver paint job, so that it had a "chrome" look to it. Both versions had a rubber decal that says "Filter Queen" on it. So, you could use either powerhead on it & make it look original.
One thing you could do, though, if you don't mind it becoming a TRUE frankenqueen & you dislike the powerhead, is replace the hose, wand & powerhead. You would do this by getting a new Filter Queen hose connector & then putting a generic Plastiflex (or other suitable) aftermarket hose on it. At that point, assuming you use a Plastiflex with gas pump handle, you could put a Eureka Sweep & Groom PN, Kenmore/Hayden PN, Wessell Werk EBK340....the list is endless. If you do use this as a daily driver, you may enjoy the on/off brushroll switch & better performance you would gain from the upgrades. And you can always put the used parts for sale on Kijiji to make some extra cash.
One last note....is the main motor original? You should be able to tell from looking at the motor, there should be a manufacture date on it. I find here in Ontario most brown Filter Queens by now have replacement motors in them....most of them have gotten to the age that the original carbons wore out, & unscrupulous vac shop owners tell the owner the entire motor needs replacing, rather than replacing the carbons. I think it's such a shame, as they are such durable & long-lasting motors. One modification you can make to increase suction & airflow, if the original motor is burnt out, is to replace it with a TriStar CXL Ametek motor. They are the same size, but due to it being a 7.5 amp, vs the original 6 amp FQ Ametek motor, they draw 90" Waterlift instead of 80".
Enjoy vacuuming with your Filter Queen! I have a Model 350 straight suction, 2 brown models, & a 2001 Limited Edition, the last of the "traditional" models, & it's amazing how well they clean!
Rob