Here is another little project I had been working on in the background and I have now tested it and confirm it works as well as the original. The PCB Gerbers are available online and getting the PCB's was not hard. The Logic chips are easy to get hold of and the ROM was not too bad. If anyone fancies a go I have some PCB's spare and can help with a build list.
This was an interface that with a press of a button generated a NMI and paged in it's ROM and let you save the program to Cassette, Microdrive, +D Disk and also let you enter POKE's and root about the program data using Hex. You would be able to look for lives, energy or whatever and make your own POKE's and find Graphics and Sprites.
This is the Wiki for the original but still applies to the new modern implementation.