Scott,
you just spent a few grand on a kart…..DON’T skimp on your safety gear. By all means buy a used suit in good condition but do your self and your family a favor don’t buy a used helmet. Who knows what has happened to all those helmets you see on EBay. You can get a nice helmet like the Bell Kart sport for a few hundred bucks and you can be sure it will protect you when you need it! If you can’t afford a few hundred for a good helmet then I seriously doubt that you can afford to go kart racing, if you really are that tight for money then forgo the next couple of races and with the money you save on travel, entry fees and tyres get yourself some decent safety gear.
We managed to get a 125cc shifter into a Nissan Pathfinder for our first few races, it was a struggle, but it’s doable!
Oh yeah when you get your kart make sure the seat fits, it should be tight so that it holds you and you don’t end up holding yourself up with the steering wheel!