Paul, the RFN design is a step in the right direction, but Lyman as a company really needs to step up their quality if they want to remain relevant in todays market. I think they now "proof" their bullet designs with lino, rather than #2. I've seen lino listed as their alloy of choice on some of their designs over the years, and bullet diameter complaints are very common. You can find decent 158 gr. RFN moulds from any of the usual mould makers, NOE, Accurate, LEE, Arsenal, and others. Also consider the WFN designs, as they are similar in profile. BRP, sadly now out of the mould business, pioneered adapting Lymans 429640 profile to other calibers as well. This design variation has been picked up by others and is very effective, and casts well.
Normally I would simply suggest trying to find an older "Ideal" mould to fill your needs, but this design wasn't available during the old Ideal days. It may be possible to locate an older used 358665 thats in spec, but trial and error can get costly. At one point I had purchased up to six different 357446 Lyman moulds looking for the version that had the oversized front driving band. I did finally find one a couple of months ago, but now I may have an example of this design from every cherry that Lyman and Ideal ever had. Now to find a four cavity version of it. I'm into "Double Jeopardy" now, where the scores can really change!