I could be mistaken, but doesn't this console take 9V DC input from a detachable power supply? If so, there is no need to step the power neither, just find a way to get the RF signal to display on a NTSC TV set, which probably will be a bit of a challenge. While I don't find any immediate results on A/V modding a SD-050 type console (Hanimex, Grandstand, Acetronic etc), it can't be much worse than most other systems.
Here is a disassembled Hanimex TVG 070C which I think is the spiritual big brother. The RF modulator seems to sit on a daughter board, with two wires for video and ground, though the signal might need amplifying using one of those 1 transistor + 2 resistor circuits plus a 5V source. The DIN connector I suppose is for hand controllers?
If this works, you have reduced the problem to how to get a PAL composite video signal to display on a NTSC TV, for which I understand there are solutions. Vice versa, a lot of newer PAL TVs would accept NTSC composite video straight away but I understand this is not the case.