Your oil pressure is on the speedo...to fit the GTt cluster you need to do a bit of messing around as we've got a moulded dash, where the GTts have a cut-out in that position.
BTW those dials aren't really necessary for N/A as one of them is a boost gauge, mainly just there for wank factor.
Stock sound system is not that great...get an amp, sub and splits to start with.
Use the best fuel you can afford, I wouldn't recommend anything less than premium!