Pretty straight forward - wondering what is a realistic, sustainable power to shoot for on a 170 mile race. Seems like I remember Chad stating some realistic ranges.
Hey Chaser!
The correct pacing percentage depends on your level of fitness you are taking into the race. For example:
One rider has a 300 FTP.
Another has a 200 FTP.
If both ride at 65% FTP for the entire race, then the first rider will finish hours ahead of the second rider. Since the first rider is spending fewer hours in the saddle, this rider can actually pace using a higer percentage than the second rider.
This makes pacing a tricky thing to assess without knowing all of the details. However, BestBikeSplit is a great resource that is built for helping you deterrmine an ideal pacing strategy for your target event. You will input your route, your FTP, your weight, and other info, and it will help you determine the best %FTP to operate during your event 
I’d highly recommend checking it out!
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I’d second @Bryce and say bestbikesplit is a great way to get a personal pacing plan. That being said, based on my experience my rides/races that are more than 150miles usually come in at 60-65% of FTP.