Krause is full of errors (although I still think they've done a fairly decent job considering the scale of the undertaking). The first link I posted to lists as KM#365 and has the VI lettering.
KM#365 I suggest. Suspect Krause listing (pictured) is inaccurate with regard to the lettering as other examples show the VI.
https://www.lofty.com/products/portugal-juan-vi-40-reis-1819-k365-vf-70-ebc-mbc-1-smsrz
https://www.portugalmoedas.com.pt/artigo.aspx?id=17619
Ooo, Paddy, that verdigris is grim. I don't see how that can be removed. What made you buy it? I know you said it was cheap but I don't think I'd give you 30p for it.