Brakes wise-
RS Turbo discs and calipers are a simple upgrade, Cossie and Focus ST170 brakes are also very popular (and work). A set of S2 RS Turbo drums for teh back are very simple but effective.

Suspension-
Koni dampers and a good set of lowering springs not dropping the car more than about 25mm. From there polybush what you can and enjoy it.

Tuning-
leave it as a panel filter and a backbox.

My brother spent a packet on his old Orion 1.6i Ghia (same engine, Bosch K-Jetronic), he ran a polished and ported head, Kent cam & vernier, Ashley 4 branch manifold and system and a panel filter. All that equated to just 125bhp and it wasn't very nice to drive in all honesty, was thirsty and not very quick. Not bad for a first build at the age of 16 though