Hi
Thank you for the comments.
The toy I used was just a cheap no-name toy that I found in a second hand store (Value Village) I used to go to these store fairly often (pre-C19) and I always searched through the toy section looking for items to convert for any number of projects. I had found a metal version that was too large and would have been difficult to modify, but eventually stumbled on this one.
So for a couple of bucks, and a dive into the extra bits box I was able to fashion this Goliath.
I would like to do something different with the wheels, maybe add 'metal' sheets like WWI artillery sometimes sported, or maybe replace them with Oshiro wheels.