I went through this with my boat when I bought it. It came with ST50 instruments which worked spradically.
To calibrate and read your ST50 transducers you'll need an iTC5 and connect your transducers to it. Then an i70 display connected to the iTC5 via a SeaTalkng network. That will allow you to calibrate the transducers via the iTC5 using the I70 display. You'll need a SeaTalkng network starter kit as the SeaTalkng network is powered separately, not through the instruments.
Too complicate matters more, the ST50 wind transducer will not work with any of the new instruments nor the iTC5 so you'll need to upgrade that instrument. Luckily the newer wind transducer will plug into the same mount that is currently on your mast head and use the same cable.
Your best bet is probably one of the Raymarine kits that include the i70 display, wind transducer and iTC5. You can connect your current depth and speed transducers to the iTC5. One comes in most of the kits but if I remember correctly, but the combined speed & depth unit will not fit the old through hull tube.
I found installing the SeaTalkng network and RM instruments to be very easy as the cables and ports on the displays are all color coded for plug and play.
Also be aware that while there are depth and speed transducers that connect directly to the SeaTalkng network, by passing the iTC5, the wind transducer is not and must be connected to compatible displays or the iTC5.
Hopefully someone has a newer and better solution for you that I'm not aware of.