Ya, the rears should fit fine although Im not sure about the brakes. Just try it and find out. My fronts are 19x9.5 with a +22 offset and 245/35/19 tires. Im also dropped on Tein 350Z H-techs.

i have 19x9.5 +23 in the front with 255/35 and i'm doin just fine dropped with z h techs

One last thing is to check the face type of your challenges, I know Volk makes different faces to clear BBK, so two rims with the same offset but different faces may or may not clear the brakes.

i think it will look very funny if u put the rear on your front because you will have a gigantic front lip... unless thats wut you wanted...

A 9.5 +23 won't have a huge lip though

^^^ exactly what they said

I think that depends more on the rim than the offset tho. Do the volks come in a "big disc" and "deep dish" version, like Work Wheels do? Cause on my work wheels my front wheels are big disc, but my rears are deep dish. So even if the wheels were the same offset (mine aren't, but that's what the wheel shop said) the lip sizes are completely different.

i have a 19x9.5 +23 in the front...and if you look through my picture threads you can see people envied my lippage in the front. so yes, you can have a big lip in the front with those specs, but i think it depends on the individual wheel itself. my vs-xx are probably different than the challenges...but it is possible...

i have about a 3.25" in the front and 4" in the rear