3-4 Coverage

We went to a 3-4/5-3 defense afetr a very poor year with the 30 Stack. I have been struggling as of late with the defensive coverage schemes and playing these spread offensive schemes. I was hoping for some input on Coverage schemes you may have been running with the 3-4 and 5-2 defense. We currently run a a 3 Deep 4 Under, 2 Deep Shell w/ an Invert and Roll coverage, Basic 1/4 coverage and a Man 2 Shell. We also run a 1/4,1/4 1/2 coverage versus trips.
any input would be great.