man.. thats an ancient plant. Nice flower
i know next to nothing about Eriosyce but E.occulta appears to be generally short and spineless. :
http://images.google.com/images?hl=en&q=eriosyce+occulta&gbv=2
although the spineless one we saw at the show was very tall. it also seems to come in spiny forms as well, and the flower is very similar to yours. so i guess it could be.
maybe something like this if its not occulta:
http://www.cactus-art.biz/schede/ERIOSYCE/Eriosyce_cachytaensis/Eriosyce_cachytaensis/Eriosyce_cachytayensis.htm