You could do that.
You could probably skip the US998 part and just flash VS99620b_03_0312_ARB00.kdz directly with Developer LGUP and the Partition DL option.
Then you just have to get Verizon to activate it. If you do the Bring Your Own Device, Verizon will offer you a new sim.
I do not think the Verizon Software update will work on the phone though. You will have to manually apply updates. It never worked when I had my
US998 flashed to VS996. But I also have the V30+, which Verizon doesn't carry. I think it was more because my IMEI is not from the Verizon device list.
Let us know how you make out.