Video projectors are best in darkened rooms, projecting onto clean white-ish surfaces (tricky in a workshop).
Projectors also have fans that will draw in dust and dirt and you'd have to keep dirt off the lens.
Projectors are best with moving images, displaying a fixed GUI on screen for hours will not do it any favours and when the bulb goes it's expensive to replace.
Projectors are also more likely to be nicked, even ones bolted to the ceiling with metal pipes get cut down by pikeys.
LCD TV is probably your best bet if you want a large image but not too high a resolution. If you want a higher resolution, then you'll want a proper LCD monitor.