First problem is to get a small turbo.Only IHI makes one
AFAIK which is small enough to be used on small engines, but its difficult to get it and parts for turbo are not easily available.Then even if you can make piping for the intake and exhaust lubrication will be a problem for which you will need to make another tank(oil).After that you will need waste gate and blow off valve.If you succed to do this much the engine will be able to take no more than 6-7 psi of pressure.Then comes problem of fueling.Its next to impossible to tune the carb for turbo engines.It wont work properly and fry your engine.So u need to fuel injection.So the amount of time and efforts wont yield the expected results.So better option is to go for bigger engine and then for turbo.