While the Raspberry Pi 3A+ technically should work, a few have found some issues with it. I would recommend against using it. Any of the other Pi 3/4's should be fine.

Here are some general assembly tips for all versions. Plan on assembly taking around 2-3 hours.

Start with the small stuff first. Typically, I go resistors, pins, fuse holders, pin headers, everything else. Doing bigger stuff first makes it harder to reach into some of the areas later. For the pins that are singles or even doubles, if they aren't perfectly straight, you can always bend them a bit to get them to line up with the board when you go to install it.

Make sure the potentiometers are turned to about half way. There is nothing like having sound blast out as its starting up if its at high.

Make sure you pay attention to directions of components! This is really important. There are some things that don't matter (the small disk capacitors, the resistors and the ferrite filters). There are plenty that do though! Like the DC DC step down converters, the OLED (make sure you choose the right set of holes that match the one you have), and the 10 pin resistor networks.

Starting with v3.5 of the board, the SMD chips are no longer needed and have been replaced by a “black pill 2.0” board. In order for this new configuration to work, you must use at least v1.34 of the firmware. Also, I have found that you may not see commands coming from the pinball machine right away. The black pill board needs to be configured by the pi, and that requires some specific things to happen. I typically find that I install the board, then let it boot up, connect to it and set some configuration, then hit reboot in the interface. It will take a few seconds, but the board will reboot. When it does, you will see the red light on the black pill board come on briefly. After it boots up again, it should see commands.