Hi Jon, will be interested to see the work on the several engines in due course. The Stuart No 10 engines are an excellent way of becoming familiar with a wide range of machining challenges, and make into nice models.
Stuart Turner used to present these No 10's as being a beginners project, but ( I've made a couple ), I would say that they take the builder through most workshop machining processes to produce the finished item as an attractive model.
Though a mill is a very handy thing to have, the vertical slide will manage a lot, but the set up time and fiddling about is more prolonged. Useful to do some similar job requirements while the slide, maybe with a small vice fitted, is on the lathe, rather than have to switch configurations too frequently. I very occasionally dig out the v. slide for a job, as in the photos ... Dave