240 front
progressive 160 to 240 rear.
as far as what you can get away with on the street...that really depends. I have H&R sports (360f/320R) and they are starting to get on my nerves a little, but I'm old. 450-500ish is commonly accecpted as the top of what people like to do...
I suppose if you got some progressive springs, like the spoons or KGMs, you could go stiffer.