Ha, I did the same kind of thing with the dodgy corrupted copy of Ultima III that was circulating at the time when I was too young to afford anything - the main map had a string of garbage items ruining the feel and also navigation (it made the game almost uncompletable. I don't know if this was an intentional move to reduce copyright infringement or not...?

If I remember correctly, there was a town called Yew, which had some druids which gave you hints towards the final answer you need to solve the game, but otherwise was not important. I worked out the % symbol represented a chest for the game and replaced the Yew town data file (the files were all separate) by hex-editing it to be full of chests. So I had effectively unlimited gold and a chance to spawn better weapons/armour for my characters.

I also ended up becoming a software engineer. Once I could afford it, I bought it as part of the Ultima I-IX compilation which came out on CD decades later.