@tomrennie
Typical and atypical grading only applies to lung NETs. I feel like GI and lung NETs are apples and oranges with many differences so you need to read about each type specifically.
I just looked up grading for PNETs and there are 3 grades. Looking at Ki-67 alone, your 8% is listed as grade 2 (intermediate) which has a Ki-67 range between 3-20 so you’re closer to the lower end of that grade. Over 20 would be high grade. But there may be other factors in grading such as the appearance of cells. Read through any biopsy or surgical reports you may have and ask your oncologist next visit to verify your grade since your case specific info will be the most accurate.