I would say TC4 in stock, as the drivetrain is very efficient, with the T2 in 19t as it is a little more forgiving.
As for the second one it would be possible, there is a speed calculator over at
www.rcracer.com.au on this thread
http://www.rcracer.com.au/forum/viewtopic.php?t=4709
just feed in some details and it will help you figure out your top speed