the fd2 civic type-r oil pump and the rsx type-s oil pump are exactly the same mechanically. what varies is the exterior. they are machined differently to accomodate their respective blocks. honda changed the lower portion of the block a long time ago.
the k20a off the jdm ep3 ctr, jdm dc5 itr, the k20a3, k20a2, k20z1, and the k24a1 out of the 02-06 crv have the blocks machined in a way that the prb oil pump used on the k20a, k20a2, and k20z1 all attach to these blocks without any modifications and work with prb oil pan.
the k24a4, k24a8, k24a2, k24z1, k24z2, k20z3 etc etc. basically all the newer generation blocks use the new design on the bottom with a raised edge.
the k24a4, k24a8, and k24a2 have been out since 2004 from the previous generation accord, element, and tsx. this was way before the rrc fd2 oil pump was ever released. so what people have done is modify the prb pump to clear the hump on the block.
the rrc oil pump clears the hump. it's machined from the factory differently and requires no modification to fit.
you will still need the baffle, chain, guides, etc. from an rsx type-s.