even with an opening hood, you can barely see much more than the radiator on one of these. most didn't have side windows so having a detailed interior was hardly worth the effort. they're blank canvas for side murals, mostly... but i remember a lot of guys going full tilt boogie on them and opening the doors, hood, even opening the roof and adding full interiors back in the heyday.
Which is exactly how Revell designed their 1/25 custom van kits- with a lift off roof to allow the interior to be easily viewed.
It is difficult to see much engine detail through the hood opening, so a removable engine cover is a must if you want to show off the engine on a van model.