Personally, I think this project looks much more difficult in 1/72 scale than 1/35. The reason being that mistakes in cutting will show up much more on a smaller model.
However, you do need to do some reasearch. For example, which way are the idler arms oriented? Sometimes they were set forward, rather than to the rear. It looks as if the strockets weren't 'moved to the front' but the hull reversed. I'd imagine that they face to the rear, but am not sure. It also looks as if the cab (turret on a howitzer) also rotates slightly, so is not fixed as in an M40... another challenge to research and build.
You can also hone your scratch building skills. It's not difficult to use sheet styrene and you'd need to be able to figure out patterns (paper, bristol board or old file folders work, as do 3X5 index cards for smaller details). I started by making interiors for my tank models (I'm old enough to remember when there was no such thing as 'after market'). If you can make a small box out of styrene, you can construct a cab superstructure for something like this. It just takes practice, patience and planning.
Some objects can be scratch built as 'solids' such as smaller equipment boxes, intercom boxes, etc. As mentioned, there are also 3D printers and resin. So, start gathering resources, drawings, etc and work on some simple scratch building. Also, if you have access to photoshop, then you can do a lot of scaling, etc. with that or other graphic programs using arsenal photographs, which you can find on line.
I wouldn't give this up, I'd just start developing the skills I need to complete it. If you need help or advice, send a me a PM.
Cheers!
Ron