I've never messed with building a 4t65e myself, but I think if you're not going to go too far with mods you should be fine with just a better input shaft and a gxp chain.
If you're planning on going crazy with boost or doing a cam swap I would be looking into the 4t80e swap or something like an F40. I bet you'd be better off in the long run by doing one of those swaps early if that's the route you're going down.
If you're planning on going crazy with boost or doing a cam swap I would be looking into the 4t80e swap or something like an F40. I bet you'd be better off in the long run by doing one of those swaps early if that's the route you're going down.