First, it seems you have two chimneys, one for the pellet stove and one for the Fireview. This is an older home. Do you have other chimneys? If so, are they sealed? If you have other chimneys, I'd make wood inserts to fit in their openings, and insulate the back of the insets.
Outside chimneys are a pain because they cause such heat loss. If I were you, I'd be sure the chimney is well sealed at the damper level, and I;d pour insulation in around the liner. One of the PH owners...I think Tony, maybe...did so with giid results.
I was interested that Woodstock told you to keep the Fireview not higher than low 500s. That's what Lorin told me, too, several years ago. She also recommended that temp for the PH. But apparently someone has told Dennis 600s is fine for the Fireview? He always burns in the 600's, and so far has been fine, Don't know if it takes a long term toll on the iron castings or not.
Anyway, I used to have a Fireview. 46x32 two full stories, full third floor under roof, with large shed dormer to the north.
Full below grade basement, 4 small high windows. Used the Fireview as my only heat. Needless to say, the house wasn't warm. However, it was OK.
From what I have learned, these are the things I would suggest:
Use larger splits. They will give you a longer burn at a steadier reasonably high temperature. Take a pedastal fan and place it several feet, up to 12-15 feet depending on your room size, away from the stove, on the side away from the air flow direction of the house, and blow the fan on low so the air glances off the front of the stove and blows toward the main part of the home. This doesn't simply try to push air warm air into the colder areas. Rather, it pushes warm air against the very hot front of the stove, where the air picks up more heat as it travels out of the room. You can put a fan at the top of the stairs pointing down toward the main floor as well, which will help to circulate air. But putting the fan the far side of the stove pointing a the stove actually is like adding another heater to the home. It should make a big difference, Try it and let me know what happens. One of our PH owners, who had a similar problem to yuors, tried this the other day (finally!) and found his home went from being to cold, on normal days, to being too hot, in this frigid weather. Get out your summer fan and turn it on. Give it a try. It will feel cool for the first 15 minutes to half an hour...don't letm that discourage you. You'll suddenly realize you aren't feeling the chilly air movement anymore.
I would expect your air temps to go up at least several degrees in the first hour.
And a PH would make a big difference. It really heats my home, whcihthe Fireview just couldn't do. My house is a lot larger than yours, though, and I'm in zone 5a, not zone 6 or 7. Woodstockaid 30% more for your home. That'a a lot. If we can't get you warmer, i'd go for the PH. But let's work with the stove for now.