Ruger discontinued the .327 federal magnum GP100 at the end of 2013 and haven't brought it back since. They also discontinued the 3" SP101 around the same time, but they reintroduced it a couple years back, only this time with a 4" barrel. The .327 LCR is the most recent addition to their .327 product line.
The .327 GP100's are great guns and you can still occasionally find them on Gunbroker, but the prices usually are $1000+ since they were the rarest of the Ruger double action .327's.
Afaik they make a Single Six frame in 327, Single Seven if I recll. I think they used to make a Blackhawk as well.