Don't use pretty print to try and parse tds, select the tag specifically, if the attribute is unique then use that, if the class name is unique then just use that:
td = soup.select_one("td.content")
td = soup.select_one("td[colspan=3]")
If it was the fourth td:
td = soup.select_one("td:nth-of-type(4)")
If it is in a specific table, then select the table and then find the td in the table, trying to split the html into lines and indexing is actually worse than using a regex to parse html.
You can get the specific td using the text from the bold tag preceding the td i.e Department of Finance Building Classification::
In [19]: from bs4 import BeautifulSoup
In [20]: import urllib.request
In [21]: url = "http://a810-bisweb.nyc.gov/bisweb/PropertyProfileOverviewServlet?boro=1&houseno=1&street=park+ave&go2=+GO+&requestid=0"
In [22]: r = urllib.request.urlopen(url).read()
In [23]: soup = BeautifulSoup(r, "html.parser")
In [24]: print(soup.find("b",text="Department of Finance Building Classification:").find_next("td").text)
O6-OFFICE BUILDINGS
Pick the nth table and row:
In [25]: print(soup.select_one("table:nth-of-type(8) tr:nth-of-type(5) td[colspan=3]").text)
O6-OFFICE BUILDINGS