[G0HZU_JMR]

It might be worth revisiting what you want from the pi match filter. I think you obviously need to provide filtering of the unwanted harmonics from the square wave but you also need to produce 4Vpkpk at 1MHz at the output of your pi match if you ultimately want a 2Vpkpk sine wave at the output of the emitter follower.

I think a reasonable target for harmonic rejection at the output would be 35dB (prefer 40dB?) If you try for more than this from a basic pi match it means you end up with a very fussy/peaky circuit that requires accurate component values and a decent coil Q to prevent excessive insertion loss.

I would suggest there are two main approaches assuming you are happy with the 270R series resistor at the HC logic gate. This defines the source impedance as being about 300R.

If you want to convert the 5V square wave to a 4Vpkpk sine wave you can either use the pi match to step up in impedance and provide the correct termination resistance for the pi filter. Or, you can step down in impedance from 300R and choose to leave the pi match unterminated. Both methods are capable of delivering 4Vpkpk at 1MHz but I think that a typical pi match will probably need an inductance somewhere around 22uH for the step up case and maybe 12uH for the step down case assuming you are aiming for a sensible Q (as in a sensible/realistic filtering response) for the network.

It might also be worth exploring how the pi match works. This can be explained without needing equations. It is really quite an elegant network and it is very flexible.