Boosting a microphone for a noisy, low sensitivity input?
A discrete stage (with PNP input transistors) into a medium-noise opamp like the 5534 is a common way of getting low noise, without the expense of low noise opamps. With a bit more care, it's not hard for a discrete stage to even beat the THAT Corp amp you linked.

NB the secret to low noise in this simple configuration is to keep the emitter resistor (R9/VR1) low - and that means high gain, which means  overloading and distortion on strong signals. So set the gain for the performance you need.

I prefer to switch between different values of R9 (with VR1 shorted) for 10dB steps in gain, the last thing you need is a noisy volume control, though R14 helps there. If you do this, keep the highest value R (lowest gain) permanently connected, like R14, and switch other R's in to reduce it, or you can expect DC thumps.

Your BC847s will do for Q2,Q4. The 857s may be a little noisier than their recommendation; I'd try, and upgrade them later if you need. 

If you can hear or measure the difference between R9=22 and R9=68 ohms there, with 68 ohms being noisier, (after allowing for the gain difference) then there's not much point improving the transistors Q1,Q3 over your BC857s.