Mazda rx7 fc swap or turbo

Ok so i found a 1990 rx7 for cheap and was thinking to start to drift at english town race way.
The car doesnt have a turbo in it so i was thinking about swaping in a turbo motor and buying a cheap inercooler or keeping the motor in and just put in a aftermarket turbo. Im on a very tight budget and not looking for lots of hp. if you have any tips about drifting or and other cheap ideas for makeing hp tell me.