You'll already have the same, or similar, cam, and you can swap the cam on a small bore engine relatively easily. Put your money into something else if you're trying to keep the cost down.
You could do the head & megajolt and see the advantage on the engine (in performance & economy) before you fit a turbo, You could also use a carb fettled for turbo charging and the rest of the turbo fuel system on a N/A car, but there'd be no advantage without the blower.
Cheers for that im goint to work on those areas firts then i will fit metro turbo fuel pump nd fuel reg, megajolt ecu (which looks a pain in the a**e) and then try fitting a 12g295 head whilst i get the turbo parts nd turbo carb mithinks