The Dynar/Heliar lens doesn't cover as much as a modern 6/7 lens plasmat lens (i.e. Symmar etc. lens). It's more like a Tessar/Xenar lens which covers about 60 deg while the plasmat construction covers about 70-75 deg. In real life at working apertures, i.e. at f/22 or so, the Dynar will cover 4x5" with some room for movements, while the plasmat will cover 5x7" with minimal movements.
But you have to try this out for your self. (I still have a bit of testing to do with a 210 Heliar f/3.5 which is a Dynar construction. I recon it will cover 5x7" with decent sharpness in the corners, but nothing much more unless I stop down to f/22, where the "magic" of the Dynar/Heliar is all gone anyhow.)
For what it's worth, I recon that any early Heliar (especially those of a Dynar construction) or even as early as being named "Dynar" will fetch quite a high price on whichever market where any "soft but sharp" buffs congregate. I.e. if you don't find what you're looking for with this lens, try to find good selling points, as these lenses are quite rare on the market.