Can't seem to catch a break

I know with our older cars problems can abound but it seems like every time I get one thing fixed something else pops up. I just replaced the hydraulic roller lifters in my 360 and now it has no oil pressure. Had good pressure before but not now. I've triple checked to make sure I installed the lifters correctly. Everything looks good. Why no oil pressure now doesn't make sense. I figure either the pressure relief valve is stuck open or the end of the intermediate shaft sheared off. Seen it before.

Anyone got any other ideas why I might not be getting pressure?

Thanks.