Right where to start
You could go and get your head skimmed two notch head gasket and get it gas flowed gas flowed not sure if you can get bigger valves maybe someone else can answer that question, well get up rated valves and valve seats triple cut the valve seats, put some cams on,
As above not sure what exhaust will fit your car but power flow should be ok. Do the panel type air filter and drill the air box..
You could go to the extent of putting some bike carbs on or throttle bodies on. Look up bogg brothers a think thats the name there pretty good at doing that sort of stuff.
Also you’ve got to think about a decent suspension set up, good spring and damper setup, some anti roll bars, strut braces to sort the handling along with some decent tyres i.e. Toyo proxies get a thumbs up from me
You’ll need uprated brakes like the valvers brakes
Really its up to you how much you want to do, am sure there are plenty of things i have missed out, as there are so many possibilities. Chris Adam is supercharging his 1.8 16v have a look
hope this helps all depend how mechanically minded you are