On 4/30/2022, John Foster wrote:
"In my MGA master cylinder rebuild kit, the two thin brass washers are NOT DISHED or CURVED, but flat. Should I slightly curve them"?

Pictures here show two different master cylinder packing kits. The thin washers in the picture above are flat, while the washers in picture at right are definitely wave washers (as original).

Yes, those thin brass washers are supposed to be slightly curved, not flat. No kinks allowed, just a constant curvature, shaped mildly like a horse saddle, two wave cyces in one revolution. Using both hands, you can use your fingers to bend the washers over tips of your thumbs to get the correct curvature.