The only extra you need is the dedicated Lee mould that throws the .457cal ball required by the ROA. You might give Fenland Rural Sports over in Warboys a call - they usually one or two for a reasonable price, and by reasonable, I mean £400-500 or thereabouts.
I have an 'in' into the US company that provides the nipples for them, should you ever require them. I'm currently making up a list of 'wanters' over here who are not surprisingly a tad unhappy at paying the astonishing UK price for these commonplace items.
There are a few of us long-term ROA owners here - mine was a birthday present in 1986, and therefore there is lot of experience and/or advice for the asking. Just don't break ANYTHING, OK?