Contact Geogina head of fittings at Roger Hansell violins. She can make the pegs to your desired dimensions. They are high quality fittings and superbly finished.
If you need to turn small diameter pegs you can make a peg shaver from a hardwood block and plane iron. Drill a hole in the block then ream hole to desired diameter. The small end of my reamer is 5.15mm. I use a LN 62 thick plane iron blade, cost now is $65.00. Any hardwood block will work, mine are bubinga.
https://www.lie-nielsen.com/products/low-angle-jack-plane-blade?path=lie-nielsen-replacement-blades&node=4104