The way the deviation is calculated when you exit the catacombs is problematic. For example, you could move 1 space and exit the catacombs. Then you roll a 6 for deviation which makes you move 6 space in a direction. So you deviate more that you actually move.
The variant below that I am suggesting tries to reproduce the deviation concept of the original game. It is pretty simple and requires no table.
When it's time to calculate the deviation, you roll a die. if you roll is equal or higher the number of space you moved, you do not deviate. Else, the deviation value is equal to the die roll.
If you want larger deviation, you can change it for "if your die roll is only greater than the number of space you moved, you will not deviate". So in this case, you can deviate up to your movement range.
What do you thik?