First, Gresham is in Multnomah County, not Marion.
The 1930 Census for Gresham, Multnomah County, South Roberts Avenue. Buel O. Boswel, age 72 (circa 1857/1858), born in Indiana to father born in Indiana, mother in the Irish Free State, a collector, public services.First married at 25 Mabel E, age 39, born in Kansas to both parents born in Maryland, first married at 25.
The Oregon Death Index is online and available through Ancestry.com and other sources.I checked it, and found no reference to a name of Buel, or of similar name.I checked for ANY Buel, Buel* (where another letter could have followed), Any Bos*, etc.This name was not on the transcribed databases.But, that does not mean he was not on the original paper rolls for any given county in Oregon.
You can "Try" the GFO site, but their online site does not indicate they have the databases/info that you need.
Since "your" Buel was living in Gresham in 1930, you should start from there.You need LOCAL researchers, not someone from Washington State.The Random Acts of Genealogical Kindness has several in Multnomah County.Ask for research in the City Directories for Gresham, if he can be found in those, he can be traced until he disappears.That would give a "possible" year of death, or MOVE to another location.These people can also do obit checks.BUT, follow the guidelines, only one research assistant at a time.