I have some of my grandad's gardening books. One set is a three volume 'Fruit Grower's Guide'. They are 110 years old. The illustrations are prints of watercolours, which are very detailed, and would give a very good guide, particularly as you say they are heritage varieties.

What I'm trying to say is that you should probably try second-hand bookshops, perhaps there are still some of these books (other than mine) around.

valmarg