These were originally invented as a hobby plane. Balsa or basswood models mostly. The throat is pretty wide open when you meet them, stock.
But there is enough room under the pin to make a new blade, that is about 25% thicker.
And that closes up the throat pretty good.
Old circular saw blades were meant to cut............. wait for it......... wood!!
And what could be easier to find than an old used circular saw blade?
About 12" is the standard gauge I like, but some of the 10's are extra thick too.
Never let a big 14 rip, or an 18 or 24" get away cheap, either.
These get cut up for larger blades, for larger planes.
yours Scott