Pity - the game is brilliant in my opinion, I liked it a lot back in the day despite being unable to progress farther than about half of it.
Anyway, the correction works. I took a look at the code block loaded after the BASIC loader program and launched by it. It is clear that the turbo loading routine starts at 24600 and is moved to 65361, where it is executed each time a data block has to be loaded from tape. If you have to load the fixing patch code in a free RAM area, I think it would not be difficult to save it as a new data block, add the relative loading instruction to the code, execute a CALL to run the patch and then let the game begin with the JP 50600 instruction. How about it?