I have a genuine Irvin jacket, bought to wear whilst driving the Morgan. Like Paul F, I found it to be only suitable for really cold winter days, it was way too warm for autumn or spring.
Were I to buy another car as open as a Morgan, i think I'd be more inclined to buy one of these excellent horse hide Barnstormer jackets from Aero Leathers. Horse hide has the advantage of being rather more waterproof than cow hide or sheepskin.
https://www.aeroleatherclothing.com/product-detail.php?id=9
