Most transmissions have 1st & 2nd as a pair, 3rd/4th as a pair, and 5th & reverse individually off by themselves. Changing 5th gear's ratio is a snap, but changing 1, 2, 3, or 4 is more difficult since you have to replace pairs of gears.

Question to which I don't have the answer: are the LS 3rd & 4th gears both longer than the GSR's? If the 3rd gears are identical then my ramblings are moot.

Either way, you should price out the following: new seals, new replacement bearings & races for every shaft, 6 new syncros (remember reverse), new 3rd gear, new 4th gear, new 3rd/4th shift hub, new intermediate gear (this is the DSM term, Honda might call it something else), new 5th gear, new 5th gear shift hub, new 5th gear, new 5th gear idler (? I think that's the term), and a couple quarts of transmission fluid.

Oh, + labor.