I make my models for chucks and arbors for M33, with the report at the origin. To get a UNC 1"x10 tpi version load this model as ‘added part' in PrusaSlicer and it will fill the M33 space like a merged-in adapter. The combination will be sliced as one unit thus overruling M33 based internal geometry. The thing will print as one unit with a one-inch pickup. 

Be careful not to move either the arbor or the fillnut separately! If the model needs to be flipped (like the longworth chuck adapter) be sure to do the operation on the whole assembly. 

This was made on request of some users. I do not have access to a lathe with 1"x10 tpi thread and therefore the model was not tested. I therefore strongly recommend to print this fill-nut separately first and check the fit. 
I left about ¼" space for a report 1" diameter. I understand some lathes have that. 

If anything needs to be improved let me know. 

Hint: you can always use this test print to build a prop chuck. Just drill a 1.5" hole into your log, mount the fill nut in with some CA glue.