Without knowing anything about your lens, it is hard to comment, but the glass should be clear without haze or scratches. There should be no edge separation. The shutter should give reliable times and the aperture scale should match the lens, the lens cells should be from the same lens design and should be screwed into the shutter so the overall length matches the manufacturer's specifications. The lens board should fit your camera. If those criteria are satisfied, you have a good lens.