9 Times Gross Rent Multiplier? 10% DP... I agree with the others that your expenses are way low and I'd expect you to find that your expenses are at least $100k/yr low. That large of a building I'd estimate 40-45% expenses at best. At a 9x GRM and 10% down, I doubt you will be breaking even.
As a life long Los Angeles person now living in Vermont, I've learned a lot of expenses in the NE are very different. I turned off my pilot light to my L.A. furnace 10 years ago and the few times it got really cold, I'd use a $15 space heater at my home. Fast forward to today, I purchased a couple obsolete municipal buildings with underground oil tanks... one is 10,000 gallon the other is 15,000 gallons. I bought a 12,000 s.f. mothballed school and it took at least 4,000 gallons of oil to keep it from freezing up. At today's prices of almost $3/gallon, that's $12k maintaining a temperature of about 50f degrees so it doesn't freeze up. Your heating expense is way low. In 60 years in L.A. I've never had a lawn... In Vermont, New Hampshire and Ohio, I now own several lawns with expenses I hadn't included.
But I bought REO and municipal surplus auctions, paid cash and paid a fraction of the median average prices. After rehab of a duplex for example, the GRM is around 2.5x...
That's a big building you are looking at... Can you afford going $5-10k per month out of pocket if things go wrong? I prefer smaller investments to be more diversified. Boston, like LA, NY and DC the prices have gone sky high. But you said Boston Area so it depends a lot on the area. In Boston proper 9x may not be too bad but if you are 30-50 miles away, you could be overpaying...