The 49ers brain trust likely has zero interest in Darelle Revis due to his salary requirements and recent knee injury.  No problem.  It seems you want to build a D-line rotation.  Here are a few good candidates available from the 2nd round on down.  Lower on the list means expected to go lower in the draft.

Margus Hunt, DE, SMU, 6-8, 277.  Very strong and physical.  Good speed.  Powerful bull rush.  Perfect fit as 3-4 end.

John Jenkins, DT, Georgia, 6-3, 359.  Overwhelming size and strength.  Tremendous run defender.  Good quickness.

Alex Okafor, DE, Texas, 6-4, 260.  Speed, edge rusher.  Very solid run defender.  Has tools to be OLB in a 3-4.

Jesse Williams, NT, Alabama, 6-4, 320.  Size and strength to be a two-gapper.  Power to collapse the pocket.  Ideal DL in a 3-4 scheme.

Jamie Collins, DE/OLB, Southern Miss, 6-4, 239.  Had stellar Combine.  Strength and athleticism to play OLB in 3-4.

William Gholston, DE, Michigan State, 6-6, 281.  As mentioned yesterday, very physical at point of attack.  Pass rushing skills need refining.

Brandon Williams, DT, Missouri Southern, 6-3, 325.  Broke school sack record (27 career).  Versatile: played all D line positions.  Could be Soap replacement at NT.