A more core rules (but not as effective) approach would be a half-orc Clr3/Bbn1 with the Strength domain. Could substitute Sorceror (or Wizard) is you really, really wanted for the Cleric levels, but BAB and armor suffers. With feats Improved Unarmed Strike and Improved Grapple.
Cast Enlarge Person (domain spell) and Bull's Strength.
Strength 28 (+9) = Base 16 Str +2 racial +2 size +4 enhancement +4 rage.
Grapple check +20 = +3 BAB +9 Str Bonus +4 feats +4 size.
Cast Enlarge Person (domain spell) and Bull's Strength.
Strength 28 (+9) = Base 16 Str +2 racial +2 size +4 enhancement +4 rage.
Grapple check +20 = +3 BAB +9 Str Bonus +4 feats +4 size.