Create grid based on item or current selection?

I feel like there must be a way to do this (and sorry if this is a repeat post, my search didn't result in answers), but I can't figure it out. I've done some non click-based recording, am working to assemble parts, and it would be supremely useful to be able to set the grid to the length of one of my items (or the current selection, doesn't matter).

are the "set project tempo / create time signature from time selection" options what you need? - (right click in the timeline)

@domzy, that almost works...except in changing the tempo for the project none of my samples line up/sound right... I've been trying different methods for this all morning, I'm just going to say f*** it, glue my items to the length of the selection and line them up that way. It's a bit of a pita, but whatever, it works, plus a weird way of working, which will mean for some weird, creative thing down the road no doubt. Thanks for the reply.