So, seems the matching networks are based on the S11 and S22 respectively.
To continue with my example of 1627MHz amplifier with
2SC5773 (datasheet):
Thanks to the thorough colleagues from Hitachi, we have at least some S parameter tables in the datasheet present.
So for example picking from the table on page 9 (Vce=3V, Ic=50 mA, Zo=50ohm), at 1600MHz we obtain S11 of MAG 0.482 ANG 141.
Now using the formula that z = (1+Gama) / (1-Gama), I can calculate the input impedance of the transistor to be zs = 0.387+j0.306
So, this should be at least a crude (but still better than nothing) estimate of an input impedance of the amp. In absolute value, |zs| = 0.493. The reference Z0 is 50ohm, so if I understand right, the amp has an input impedance of 0.493*50 = 24.7ohm. Interesting. No idea if this is correct or how far from reality, but at least gives idea, what kind of matching network would be needed.
As a matching network for the amplifier input, it seems a simple LC lowpass network should be enough, with the series element connected against the input terminal and the shunt capacitor against the transistor. How to calculate these values still I have to figure out, so gimme a while...
EDIT: Well, I made it the other way round. The series element should be against the smaller impedance, while the shunt against the larger one
EDIT2: Oh... it may not work at all that way either. Doh!