This should have a 531 head and an A cam, but it’d be worth checking before buying it- if you want a 531 that much that you’ll buy a whole engine for it that is.
Unfortunately the rest of the engine isn’t a good starting point for a big power build- smaller 9mm rods and no oil squirters.
http://https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F 283296530350
Cheers