In other words, this one:
https://www.moto-lita.co.uk/steering-wheels/offset-wood-rim-wheel/. If you have PAS, you could easily do with 13". If not and you do not fancy the offset look, 14" might be a solution, but you gain only one inch compared to the one you have. With a dished wheel you gain a little more, so there might not be such a large difference between a flat offset and a dished 14". I believe 13" on a 4/4 or +4 would be ok, on a +8 or a Roadster far too heavy without PAS.
By the way, this thread would be better under the "Classic Morgans" section, you would get more answers. Perhaps more confusion.....