Curt,
You can install the EI CGR 30P in your Tiger. Mine was installed in my 91 AG5B in March of this year, and so far I really like it. It has replaced all of my primary engine instruments and I like having MP and RPM displayed at the same time along with cylinder and EGT temps. AA5’s are listed under True Flight Holdings, LLC which holds the rights to most Grumman, American General and other versions of the AA5’s.
As far as I know, JPI’s systems (730’s or 830’s) cannot replace the primary engine instruments at this time. I believe the JPI 900 (930?) is certified but it’s way expensive. But be aware, the battle between JPI and EI fans is intense and no matter which system you choose, someone some where is sure to tell you that you made a bad choice.