Thanks John,
As recommended in the earlier response I downloaded gspot and media info, and oddly enough (as I suggested I’d read in another thread), rendering out in that template (NTSC IMX 50 Widescreen) resulted in a height of 512, so it did sort itself out. The only issue I ran across was the extra audio channels, but everything else matched spec, so I went with it and hopefully it will work out fine.
Thanks everyone for your help!