New custodian of a wonderful 1942 Willys MB in UK

Hi. Thanks for adding me.
My father in law restored a Willys MB in around 1990 to an extremely high standard but sadly died soon after so the Jeep sat in a garage until two years ago when my wife and I had it commissioned and serviced and it is now running well and is giving us enormous pleasure. It was used as a prop in a film a couple of weeks ago and stole the show! It covered 240 miles that day without a hitch. I’ve attached a pic.
I’m enjoying tinkering with it and getting little details sorted.
I have one question that I’d be very pleased to have answered concerns the machine screws for the fuel sender on the petrol tank. I changed the tank for a US made reproduction and I have a new sender to fit but I don’t have the small screws which I’m guessing are US standard thread size, so probably not available in UK fastener shops. I can fit a 3.5mm drill bit into the threaded holes in the tank. Does anyone know the size the screws are so I can find them online? Any help gratefully received! Thanks.