Which Mainspring to Buy?

So I went deeper down the mainspring rabbit hole today. Can't get my ail-express winders to work with it and figure I may as well buy a new one and just be done with it. Watched the Watch Repair Tutorials video on calculating and picking the right size based on the barrel and measured it myself to the best of my ability. Specs came up really close.

I measured...

1.4 height, 0.1 thickness and about 340 length

The calculations based on the barrel measurement worked out as follows ...

Inner Diameter: 9mm

Depth: 1.8 - 0.1 = 1.7

Lid thickness: 0.4

So his formula gives

Height: 1.7 - 0.4 = 1.3

Thickness: 9/87 = 0.1

Length: 9 x 35 = 315

So I figure anything close to 1.4 or 1.3 in height, 0.1 thickness and between 320 and 340 length will work right? So I head off to cousins and they have a couple of options. The watch is manual wind so non-automatic seems fine.

1.30 x .10 x 320 x 9 Non-Automatic - GR3255

and

1.40 x .10 x 320 x 9 Non-Automatic - GR3665

Do I go with the 1.4 I measured? (Have cheap calipers) Or do I use the calculated 1.3? Does it matter?

Also worth noting that my mainspring doesn't have a bridle to speak of. Just a tiny bit folded over at the end.

Other alternative is to manually rewind the existing spring. Seems wrong.