Sal's Dad says:

I have never been able to find info on CG approval/endorsement/preference
for any particular flotation.

They won't recommend, as it would:
a - restrict freedom of choice.
b - would favour one manufacturer over another ( since most cores are a
patented chemical brew made by only one company) Note the word "most"...
c - THey would have to re-write the regs every time some new process/chemical
appeared on the market.

It is up to you to find a core that meets the requirements, and is in your
opinion the one you want.

Steve