I've got a copy of World Class Leaderboard for C64 coming complete with the dongle, the picture showed the resistor between 1 & 6 for that game

Just remembered I made a B.A.T. II dongle for the Amiga a few years ago, found a post on EAB that said it was serial port dongle with a resistor on pins 20 & 5 + a capacitor on pins 5 (Positive) & 7 (Negative). Values I got from Keir Fraser, 15k resistor and 0.22uf radial capacitor.
Also, Keir helped me make a Robocop 3 dongle for the Amiga but that was more complicated and I've mis-placed the dongle but from the emails it was:
Dual Flip Flop IC 74HCT74N and a female 9pin D-Sub wired as follows!
74HCT74 --- 9 Pin D-SUB
1 (1/RD) ---> 7 (+5V)
3 (1CP) ---> 6 (Fire1)
4 (1/SD) ---> 7 (+5V)
5 (1Q) ---> 1 (U)
7 (GND) ---> 8 (GND)
10 (2/SD) ---> 7 (+5V)
11 (2CP) ---> 8 (GND)
12 (2D) ---> 8 (GND)
13 (2/RD) ---> 7 (+5V)
14 (Vcc) ---> 7 (+5V)
Also, connect Pins 2 + 6 on the 74HCT!