i don't know why people are giving you a hard time about doing the conversion. why everyone else is trying to get the 'jdm' look, your being more original and i give you props for that. yes, they do make a r33 bodykit for the s13. you can check out
http://www.visracing.com. they don't have it on their site, but they do make them. i almost bought the kit for my s13 until i found out they were on back order for like a year now. i had also bought r33 tailights to install on my s13. by the looks of it, it doesnt look like it'l take much modification to install those. anyways, good luck with your car.