It's a common misconception amongst some inherently less tuned in people that everything needs to be bigger and whilst this stands true in some cases, quite the opposite is true in others. What would you say if I was to tell you your engine is capable of flowing close to 400bhp regardless of what engine code your head is. Then why might you ask would one want to port, port match, remove castings and polish an engine I hear you ask? Efficiency - it's more than just vmax volume of gas the head is capable of flowing but also equally as important: velocity. Both these parameters are related as you can imagine, by optimising the flow, one can potentially attain lower egt, more even swirl filling etc. etc. If you don't grasp the maths behind this (or optionally have access to a flow bench and some modelling software) I suggest you just leave this alone.
These are by no means "old fashion tuning" and is still very prevalent today. There are many who have done head work on the 20vt and ultimately whilst one can potentially (I say can with great caution here), it's more likely one would do more harm to the performance than good. In terms of real world gains, it's unlikely you would notice a difference in your vehicle unless you was pushing something pretty hard, i.e. really high egt. It's one of them things that some would do while the engine is apart as they're going to submerge the cylinder head in a chemical bath afterwards anyway.
