I just went out to the garage with a caliper, looks like 1.8” best I could measure. Definitely looks like the spring seat was cut and it has some shims/locators at the bottom.
If it's really 1.8 and you're using those springs, you know they have 165 on the seat at 1.8. So that's your camshaft's needs on the seat. It cannot have a ton of lift.
