Hi Brooksie,
I'm in the final stages of getting my G-Force engineered and overall have been very happy with the kit. I'm not as mechanically capable as I probably should have been to embark on such a project but came through unscathed. Mind you, I called on peoples help along the way. I got the Mark I chassis as I didn't need the extra torsional strength of the Mark II. The Mark II is more suited to big block applications. I dismissed the Toyota Crown option based on the fact that one day I may sell the car, and in my opinion, it would devalue the car. Also, not sure about the amount of flex in the crown chassis.
The Mark I is impressive - when I lift from any corner the whole side of the car lifts together as one. The G-Force is essentially the same as an RMC.
My word of advice would be to take a good look around at all the kits. Most of the kit makers are always improving things so keep this in mind - I believe Ian at Classic Revival has started using a new body mould for example.
If ever you're in Melbourne, there are plenty of us guys building different kits (probably in NSW too). Any one of us would be happy to show you.
Happy hunting.
Adrian.