This is on me for doing this, however I will also just say so in case other people are like me and want to continue from where they left off.
You CAN use a 0.5 save in 0.6 if you want to continue from your last save. However, there is one glaring issue and one funny issue.
The funny is, apparently Jane is hiding an entire car somewhere because you need to import an image file called "Vehicle" into 0.6 to get the save to load. For me I was just in a repeating error loop until I did this.
The glaring issue. You cannot use the "Use Item" command, which has essentially replaced the inventory, which means you WILL need a new save file in order to do some new content. No, the Vehicle is not related, I started a new game to see and that worked fine.
I am not asking this be remedied or anything, it is an old save why would you? It is on me for trying. However, I personally did not want to start from the beginning. I am mostly just saying this so if other people want to save the time, they can save time by just starting over.
And seriously, Jane, where are you keeping the car?