In the past, my racing HR was mid 160s. If I hit 170, I start to not feel good. I can hold that for a little and can do it at the end of the race, but when I've hit it to early, it's never gone well.
The only thing I wonder is if that number has reset at all with the MAF training. It's also why I was surprised to see 159 at 8:00 min pace last week because that's definitely lower than usual for that speed, especially 9 miles into a run.
I'm leaning toward doing a combo of what you suggested and
@bushdocda. Start slower, keep HR in the 150s for the first 5K. I'll just see what that ends up being. Try to get to 8:00 for the next 5K if I can keep it in the 160s, then push hard for the final 5K with whatever I can manage.