If you’re able to create any levels, I’d suggest maybe a dozen main topics, with related sub topics. For example: “interior”.. sub levels include seats, hand brake, battery, sheet metal, gauge cluster, pedal box, trans tunnel, mirrors, gauges,... etc.
I’m a fan of more categories. Included would be not only the basic build instructions, but user input, hints, tricks, tools, upgrades, etc. Tthis goes for every subcategory.