Headset on Custom Frame Build Urgent!

OK... I feel like a complete idiot...

I bought a custom frame and individual parts about 9 months ago and have only just gone on to fit all the parts... immediately before a major expedition... and it turns out that despite decades of experience I've gone and mucked up my choice of headset.

I have the following;
A straight 44mm Headtube. 44mm at the top and 44mm at the bottom

A tapered steerer tube
1.5 inches at the bottom
1 1/8th inches at the top

Can anyone tell me a model I should get, please?

I'm stuck abroad (Japan) don't speak any Japanese and need the headset, like yesterday.

I had bought a Chris King Inset 5 which although is the correct sort of headset, (in terms of straight headtube and tapered steerer) is for a straight 49.61mm Headtube.

I've checked on the internet but as ever the choice is bewildering, it needs to be sent asap and I cannot make another mistake timewise.