The mornings in standard TSA lines can be slow, but I can't see it being more than 20-30 min. The PreCheck in the morning at PDX is amazingly quick. Its usually under ten minutes from curb to gate with PreCheck. I think your plan will be just fine, your buffer is probably lounge time.

I will share my favorite Priority Pass use at PDX is Capers Restaurant. We load up for the flight with meals and beverages. But the AMEX PP does not offer this, so you have to have the CSR version.