Turbo engine for 300bhp is super easy and lots of parts off original cars engine like inlets can be used , super charger is good but can be very expensive to buy and setup correctly.
black top engine
pistons and rods if you can afford and you've got 500 bhp bottom end
erst exhaust manifold
rs 1800 inlet manifold
injectors
standard head with updated valve springs
intercooler
turbo
and your easily gonna be around 300 bhp

cheers paul