Alot of work and money for very little gain...
Need manifold for inlet and exhaust
oil feed drilled in block and a oil return put into sump
lower the compression ratio in the cylinder block
gaskets, pipes, air filter,
re mapping of fuel, or at least the correct fuel/air ratio so u dont burn valves out, even then ur looking at 20 bhp gain, spend another £300 and get a intercooler and u looking at 30 - 40 bhp top over all...
Buy a vr6 for £400 and plonk the engine and box in yours, 180 bhp for £400 and a couple of saturdays work...
