You said no airbags and then asked if it could pass modern standards. No of course not if you crash at speed you are dead

Maybe. if you can get it under UTV\ATV rules. I'm not sure what those are but you get a loteof options. It wouldn't be street leagal, butiin some cases you can drive on a road between off road trails - check local laws. If you want to sell this have your lawyers look as theremay be other exceptions - could you call this a farm vehicle if you add some accessory?

Mahindra started out by cloning the Willys and they sell something relatively modern in the states called the Roxor

Straight from the original blueprints: heck no, consider the lack of seatbelts to say nothing of emissions.

With a bunch of engineering tweaks but staying close to original: maybe you could get it to be legal, but almost nobody would buy it. The gas mileage would be terrible. Maintenance would suck. Cars have EFI instead of carbeurators now for good reasons. And a car with no air conditioning would be miserable in lots of places.

Anyway if you wanted to do a project in that spirit today, I'd suggest making it all electric, but designed simple, like an e-bike on steroids instead of like a Tesla (which is more like a computer on wheels). Use LFP batteries instead of the higher energy but much more finicky and dangerous Tesla style packs, have some rooftop solar panels, maybe something like a street legal Kei minivan:

https://www.vantagevehicle.com/collections/electric/products/electric-passenger-window-van

You can buy those used in the US for around $5K but their top speed is 40mph, and they are only legal to drive on slower streets. I was a little bit tempted but decided I needed something that can drive on the freeway.

I want the SAS variant with the Vickers machine guns attached. I don't think I'm allowed one.

They do. Mahindra roxor.

This guys sells a boxed/crate 1942 replica if you are interested

https://thejeepsterman.com/products/jeep-in-crate-mb-1942-willys-jeep

Yes. Because it is. https://www.hotcars.com/this-country-is-still-producing-ww2-willys-jeep-parts/

Absolutely not in the states though. Whatever came after passing safety regulations wouldn't be a Willy's Jeep.

The entire design would need to change to meet safety standards. I don’t know that the ease of assembly and cheap low cost would survive the safety requirements.

A lot of the complexity of modern vehicles encompassing not just drivetrain but also exterior design is to squeeze fuel economy from a stone. The shape of the Willy’s isn’t aerodynamic and that’s putting it mildly. Modern standards for body panel tolerances raise component costs. Full time 4x4 is awful on paved roads and terrible for fuel consumption, so we would now use a transfer case or a AWD system, which add cost and complexity. The simplicity of the suspension design made it a death trap at speed - good for off road, no good at 70mph.

My point is that as much as I want a repairable, simple thing (car, computer, etc.) we’ve developed so much technology that even when a thing is designed for repairability, it’s going to need specialized skills to some extent - can’t fix everything with a hammer anymore. Might need a torque wrench.

The current wrangler is an idea of what a modern Willy’s would be like. It’s going to be a $40k vehicle.

ETA - Ineos Grenadier is a modern take on the classic Land Rover. Similar concept, similar departure from simple an cheap.