blue99SS

Ok guys, my 99 SS is in the shop right now having all the stuff in my sig put together. I also told the mechanic to put on LS6 springs. Well it sounds like he got LS7 springs by mistake because he telling me that the spring is taller than the v'stem and that there will be a lot more seat pressure. My question is do the LS6 have taller install height than LS1's? They should have a little more seat pressure but not alot right? Don't LS6's install just the same as LS1's? Also, I know that there are like three different versions of the LS6 spring (red, yellow, green?) which is the best and any part numbers to go with if at all possible? Thanks for the help, any comments/advise are greatly appreciated.