Bespoken appears to be the original term before "bespoke" was used to mean custom-made. Its usage in that sense is now archaic and rare:

[Bespoke][1] (adj.):

• "custom or custom-made, made to order," of goods, as distinguished from ready-made, 1755, the same sense found earlier in bespoken (c. 1600), past participle of bespeak, in a sense of "to speak for, to arrange beforehand," a sense attested in bespeak from 1580s. Now usually of tailored suits.

Etymonline [1]: http://www.etymonline.com/index.php?term=bespoke

Bespoken appears to be the original term before "bespoke" was used to mean custom-made. Its usage in that sense is now archaic and rare:

Bespoke (adj.):

• "custom or custom-made, made to order," of goods, as distinguished from ready-made, 1755, the same sense found earlier in bespoken (c. 1600), past participle of bespeak, in a sense of "to speak for, to arrange beforehand," a sense attested in bespeak from 1580s. Now usually of tailored suits.

Etymonline

Ngram bespoke vs bespoken