Any kind of boost equipment is, by the nature of what it does, a limited life item. The person selling this item is probably an up and up guy and the unit probably functioned perfectly when it came off his ride. However, you have no idea, really, what's going to happen when you bolt it into your ride. Who's gonna pick up the bill if, after three or four months the unit goes into the crapper. I would be willing to bet not the guy who sold it to you. I wouldn't pick up the bill either, if I sold it to you and you shouldn't expect him to. You want to buy any number of used parts, no big deal (NBD) if you know what to look for. Used exhaust, NBD. Wheels and tires, NBD. Used carb, even used heads, NBD. But a huffer is a crap shoot. I would give this some serious thought before dropping the price of a fairly nice engine rebuild on an unknown item.
Depends on what you want it to do. Roots/positive displacement blowers work low to mid range. Centrifugal blowers like the one you're looking at are more mid to top end. Boost in any form is going to flat run. Pick your poison.