Hi Paul, for conveniently boring this sort of smaller sized hole there is a lot to be said for making up a few small boring bars yourself from silver steel, the length and shape of the cutting edge can be produced by turning and filing the s/steel in its unhardened state, and then the tool can be hardened + tempered, and the final edge put on by honing with a slipstone.
It is easy when filing the cutting edge to be sure that you give it the clearances that will work in the small dia holes.
The tools work best in conjunction with a simple holder made up to fit the tool post arrangement that you are using. There is much about all this in the articles and books written by the late Geo. H Thomas, who designed a lot of tooling for the model engineer and wrote the designs up in Model Engineer magazine. Dave