Well, I got it done. Although I still have to get hold of a torque wrench that goes up to 220 Ft lbs (about 300Nm) to tighten the bolt.

To break the bolt I made a simple holder from a 2" wide x 1/4" thick x 15" long aluminum bar. Two 3/8" holes drilled at one end that are spaced apart the distance between two of the crank pulley bolt holes (2 1/2" on center, which will leave a hole between them) and about 1/2" from the edge of the bar and a 1/2" or so from the end of it. between the holes I cut a half circle arc to allow the 27mm socket to freely turn. Doesn't have to be neat, just as long as the socket can fit in there. I secured it to the hub/balance with two 1.5" M8 bolts with 3/8" spacers (Steel bushings from the hardware store) since I left the balance on the hub. After it was bolted to the hub/balance i used a Jack stand to support it horizontally. With a three foot pipe over my 1/2" breaker bar the bolt came off easily.
The hub came off very easily with a puller. Best of all it could be put back on by hand and some gentle nudging. The Haynes manual said it would be necessary to heat it up to about 120° to be able to fit it back on, but that certainly wasn't the case.
Before I attempted to pull on the lower timing cover I tapped it all around with a mallet until it sounded hollow everywhere. It slipped right out with no damage to the oil pan gasket at all. Lucky I guess.
With the cover off the guide rail and two cable ties around the chain/cam sprocket to keep the chain in place and a finger firmly on the chain on the underside of the crank gear (to keep the chain in place there as well) I manipulated the tension rail out on the left side to have room to angle the chain away from the workings, wiggled the sprocket off the cam and with some difficulty managed to get the guide rail backing out of the case (always keeping my finger on the chain under the crank gear. Manipulated the new one in and set the sprocket back on the cam making sure the chain is taut on the guide rail (intake) side.

the bottom of the rail should be secured first. one of the rail pin holes will be oval which helps the installation.

Hope this info helps someone else.
Thanks