The dimensions you post are pretty typical aftermarket hot rod parts. Here's one source for Pete & Jakes rear shocks, note this is not necessarily an endorsement for or against this vendor, it's a source for the Pete & Jakes part number;
http://www.rjays.com/Pete_Jakes/PJ_Shocks-01.htm

BTW, the actual P&J site doesn't give dimensions or prices so that's why I used a dealer site.

Another source is Chassis Engineering for their own shocks: http://www.chassisengineeringinc.com/page73.html