Hi Craig
In my experience, making new holes and filling the old ones with ABS haven't cause any issue with cracking or something like that. I would recommend to make some test first with a piece of ABS , once you feel confidence with the procees, you can do the fix.
I have another tip , I have recently used for this fix :
1- Glue a little circle of ABS behind the old hole to give some support (I have used " Zap a Gap" glue for fast dry.)
2- Fill in the front of the hole with another small ABS circle
3- Apply a bit abs paste if needed just to fill any minimal gap.
4- Sand a bit with a super fine sand paper and Polish with Car polish to give some shinning or glossy finish.
Hope this can help.