I would get:
For the keyboards, pedalboards, and buttons:
https://www.midiboutique.com/hwce2x
-With this, I would also get the appropriate amount of Keymusx64 or SM8X8, depending on your needs (Keymusx64 if your keyboards have a common return rail, the cheaper board if they don't), and associated connectors. I have extensive experience with the board with only 4 inputs, and it is pretty easy to wire, and quite safe.
If you don't have a lot of electronics experience, I would suggest you get local electrical help with the wiring of the SAMs portion. Some SAMs circuits can draw quite a lot of power, so I would recommend being careful how the circuit is wired to prevent short circuits/fires and electrocution.
Also, which hardware you need to buy depends on the power consumption of your particular SAMs and how many there are. In general though, you would need a MIDI decoder and a power supply for that. Depending on the current consumption of your SAMs, and how they are designed, you may also need a driver board and power supply:
-https://www.midiboutique.com/mddp128u
-https://www.midiboutique.com/dp64P
-https://www.midiboutique.com/dp64n
-https://www.midiboutique.com/psu12-8.5
-https://www.midiboutique.com/index.php?route=product/product&product_id=270
Which decoder board you need depends on how many SAMs you have and what the current draw for each SAM is (I'm not familiar with Comptons, but some SAM designs require power for a switch and power for the magnet, some are all in one I believe). If you know the current draw for the SAM, we could steer you in the right direction.
In addition to all this, you would need the appropriate electronics tools/wire/etc.
If you are handy with a soldering iron, I would buy the versions with pins. Otherwise, get the screw type connectors for everything (and the additional boards to convert pins to screw type connectors (https://www.midiboutique.com/bo34))