[Phat Mack]

You think the 8 upcard will find a hand to play 45% of the time?

I do. An 8 up-card is stronger in any-any than it is in eight-or-better because of its ambiguity about direction (hi or lo). In 3-handed any-any, an 8 in the door is second in power only to an ace.

I raise or fold here, not call or fold. If it comes low/low on 5th street, I may want to slow him down a little. If it comes diamond/any or low/brick, I'd keep up the aggression.

My "fold-or-play" here is based entirely on my ability to outplay villain on later streets. It's not about showdown equity so much as it's about whether you can make any money off the guy when it's board against board.

From your thumbnail description of villain, I'd probably fold fairly often.