I JUST did this a couple days ago on a big block. I used these. Pound the biggest one in there and remove with the biggest crescent wrench ya got. Easy peasy japanesey.
See the two big notches at the top? The factory tool is a straight blade screwdriver on steroids, it fits all the way across an then some, it is as wide as the notch. The rear one looks normal, the one in front is a bit worn down.
