Well, to answer my own question....I did it!
Entered the 100 k event, and was surprised how casual the the whole thing was. At the registration table located in front of a Primary school I paid my $80 dollar fee ( quiet steep for a small country event, but hey, it was for a good cause...CFA and Ballan Hospital.) and all I got was a blue wristband, no bib number, etc. I then joined the ranks of the 100k group at 8 o'clock start time, which would have consisted of less then a 100 cyclists. To say it was a beautiful morning would be an understatement. Perfect start to an enjoyable ride of great scenery and rolling hills through Central highlands.
After 65k's the route came back to Ballan and after being lulled in false sense of security, I was in shock what was to come. The last 35k's were the hardest I've done ( I have done Degani and Otways). The rolling hills turned into monster climbs around Greendale and to top it off, the prevailing headwind picked up quiet a notch, which made every pedal stroke that much harder. The only respite was when I did get up the hill, the descent was a welcoming relief! About 3 k's out from the finish line I developed quiet a build up of lactic acid (not enough training) and had to virtually walk for a few hundred meters so my legs wouldn't feel like led. After the finish line I took advantage of the free massage on offer...ahhhh! ....the legs felt so much better