Hello IcePack,
I have 185/70 15 Vredestein Sprint Classic tyres on my 4/4 Sport with the original rims.
Of course a question of personal taste if you prefer the taller look or if you prefer to have better filled wheel archs.
For me it looks fantastic (also the classic design of the tyres) - not as small as the original size and not too large which means not to modern looking.
I did a lot of modifications on the car but changing the tyres was an important point (and I sold the original tyres via internet for a good price).
Enjoy your MORGAN!

Kind regards,
George