You've got Bosch LE Jetronic on that mate, and you can't rechip the ECU because it's an old analogue system and not digital. The trouble with LE Jetronic is that it's an economy biased system and doesn't respond to mods. The very earliest E30 318i's (i.e LHD cars made before Agust 83) used K Jetronic which was better but forget about trying to find and fit that, you'll never do it.
The standard 318i cam is crap, and it really restricts power. If you can find a good used one, look for a 2002Tii cam which will fit; the distributor drive on old 2002 and earlier E21's runs the opposite direction to an E30 so you'll have to a) use a 2002 distributor complete with nasty points and condenser
or run an E30 distributor with the plug leads reversed (v.easy).
As for the injection, I would personally get rid of it and use a pair of 40DCOE carbs. Secondhand Webers are generally a load of shyte so a complete kit with manifold is best. Trouble is, they're Ԛ£Ã”šÃ‚£Ãƒ”šÃ‚£Ãƒ”šÃ‚£Ãƒ”šÃ‚£Ãƒ”šÃ‚£ although the Mikuni kit that Jaymic sell is okay and probably comes jetted for a 2 litre.
For the injection, the big restriction is the throttle body which is tiny so you'd need to adapt something else, maybe one from a 320i. Then you'd need to get more fuel in and as you can't alter the ECU you'd need either bigger injectors from a 320i or raise the fuel pressure with an adjustable fuel pressure regulator.
But, for decent power you're wasting time and effort with this injection system -you need CARBS
But then, as MasterBates said, if you want serious power, then carbs are they way to go, but then you will totally lose any respectable fuel economy. A programable injection setup is the best of both worlds, but then they don't come cheap.