Well the deed has been done...
The thread cutting method did NOT work. I could never get the thread to even start cutting the plastic before it would break. I even tried using my Xacto saw to start the cut and then insert the thread. No dice. I also tried my Xacto saw, but the blade was too thick to cut around the corners. SO - knowing that I was going to use S & P's excellent fenders, I knew I could 'hack' them off - which I did with a set of tin snips. Then I used the snips to cut around the corners and along the hood line. Doing this worked REALLY well - right up until I cracked the drivers front corner of the hood cutting through the thicker part where the grill is to be attached later. However, it is a clean crack and I am sure I can patch it.
I am happy with how well the hood fits, BUT I wanted to extend the cowl a bit for more of a Pete look so the fit may not matter as much. Anyway, after months of not working on Old School I am back in the saddle again.
Thanks for looking - as always comments are welcomed.
Note: The 'dirty' look around where I cut was intentional - I made a wash out of black paint and thinner - which I then applied around the area I was cutting. This made the indented lines on the cab where I wanted to make my cuts turn black. I cut just outside the black lines and then used a file to remove the black and I had a nice even cut right along the existing body lines.