What are you intending to do with the Goblin? Daily driver? Weekend cruiser? Racer? Will you be driving in traffic or out in rural areas? Are you tall or short in stature? All of these questions, plus many more you will need to mull over before making a decision.
Many of us, like myself, being tall and large, chose the extended chassis for legroom and headroom. Since my car will be seeing city traffic and likely some road coarse time, I went with the track frame. This works for me. What you choose is personal and whatever way you go, the members of the forum are always ready to provide advice and technical help.
And BTW, you may want to get a Build Log page set up since you're starting your adventure.
