Luc's Mexican Mangosteen grafted on Imbe

[snowjunky]

Hi All,
Is Luc's Mexican Garcinia compatible with Imbe rootstock long term?
Does anyone know of a healthy Luc's Mexican Garcinia on Imbe rootstock?

I have two 10ft tall Imbes in the ground that still haven't flowered.  How long do Imbes take to flower?
So I'm thinking of grafting Luc's Garcinia to them. 
I have a 3 year old Luc's seedling that's 10" tall, no kidding.  They grow so slowly here in Phoenix, AZ.
Imbe is the only garcinia that I know of that grows well in our 8+pH clay soil and take the Phoenix sun and summer heat. 
It's also cold hardy down to 25 degrees.
If they are compatible long term, then Luc's would probably be better off on Imbe rootstock than on it's own roots.

Thanks for any info.