The 4G is about 13 oz or about the same as the Pate Tarpon.
I wouldn't hesitate to use it on a 10wt and on up thru a 13 wt. Probably your best bet is an 11wt; ok for the Keys, a little big for Belize but still useable for the really big fish here at Homosassa.
And as for the length, a 9' is pretty much the standard size. But I would look for a blank that is very fast.
I used my Tarpon on a 9' for a 10wt for 15 days of Permit fishing in Southern Belize and made lots of casts, about tore my arm off tho.