I have a 40# modern grizzly and I have 2016's that are a little too weak at my draw (28"). They are a little too long (31.5" w/ 100gr heads), but I think if I do 29.5" with a 125gr head, they should be just about right. I currently have my strike plate built up a bit as well.
I would go a little bit stiffer for a 50# with 30" arrows and 145gr heads.
Also, are you sure .5" is enough to keep the broadhead off the shelf? On my bow, I need a solid 1.25" beyond my draw length to get the head to clear the shelf.