If by this name you mean health insurance that is guaranteed, then your domain is improper as per the English language.
guaranteedhealthinsurance.com would be proper English.
As such, given this and the length of the name, I do not see much value.
Also, I have never heard of guaranteed health insurance,
but I have heard of guaranteed life insurance.
I am not saying there is no such thing, I just never heard of it. Maybe guaranteed health insurance means health insurance that does not look at or care about pre-existing conditions?
Keywords Everywhere plugin shows only 40/mo on both phrases "guaranteed health insurance"
and "guarantee health insurance" so it is a very uncommon phrase. "Guaranteed" is used for life insurance, not health insurance.