My true south sat is 72w and i can get from 30 west to 135 with a 24" actuator.Since your true south is at 79 i would say you may make it to 139 but then down to 30 may be harder to get.
OK so I was looking at your equipment list in your signature and didn't see a Cband dish listed.
I'm on 79* and I can get 139 to 37 before I run into physical limitations of the polar mount. This is with a 24" SuperJack and VonWeise actuators. I "probably" could modify some stuff and get further back east but I got trees in the way and I've already cut down about 10 going west with my SAMI dish so I won't cut any more.
FYI IMHO 139 isn't worth trying to get unless you're into radio and there's about a thousand of those channels on that satellite. I use 139 more for tuning my dish than for entertainment.
on my 10 footers ive had to modify the mounts to get more travel. id say they do about 34 degrees to about 145. actuators on the west side. i had to add approximately 1 foot extensions to the mount ware the actuator attaches. this extension moves the actuator to the west and allows for alot more dish movement east before physical contact between the mount and actuator. ill look for a pic of it.