When I did the timing belt on my 2.7, I just used a pry bar and penetrating fluid while making an effort to release the sprocket evenly all the way around.
EDIT:
There's no doubt I also used my trusty rubber mallet to get it off (read: beat the **** out of it).
I went at it with a flamethrower, worked like a charm. Only needed to pry on it gently. Had to put the gear/sprocket with the brass like backing on a flat anvil to gently tap the small ring on the back, back down.
I didn't want to hit it out of fear it would bend, or cause my bank 1 cams to jump. I was holding those on with 4 timing belt pieces folded in half and wedged into the gears on top and bottom, a 2nd pair of hands holding 2 17mm sockets/wrenches, and even 2 more pieces of timing belt so the gear + Belt could be vice gripped. The front tends not to slip if you put old cut & folded timing belt pieces in, but those 2 cams in the back are a nightmare. Had it slip a few days ago while doing the timing belt, despite the usually fail safe wedged old timing belt pieces method. No damage done but still annoying to line things up again, with so little space.
My Crankshaft seal was so gone that it was spinning in its socket.. New seals in. Previous leak is gone. Cars running well, gonna check for drips for the next few days.
For anyone that comes up with this topic via searching in the future:
Only go with the heat option if you have a crank seal to replace the old one.
This seal is best replaced at the same time as you do a timing belt.
Don't bend the brass backing behind the gear. It'll have to clear your Crank position Sensor, as it spins. Also remove your Crank Position sensor before you start playing around with it.
Even a pretty seized gear comes off if it's heated up.
Don't burn your fingers.
