I have used a 2x6 with lag bolts to hold the large freewheel cog.
Also, there has to be a very compelling reason to break open a freewheel body and service the pawls and bearings.
In the past, I have soaked the freewheel body in solvent and dripped Phil’s tenacious oil, spun it and repeat, and let the oil soak through the body.
There are some of people here who have completely disassembled a freewheel body, and I take off my hat to them, but I highly doubt you can replace any springs or pawls. And if the races are bad the freewheel is toast.
John