The RB woild be my choise for the price.Even the low end s7 is plenty fast & RB at least in this country is the cheapest motor to rebuild by almost 1/2 & it comes with a pipe.The pipe & header will set you back anywhere from $70 to $170.A smokin deal like that is the hot ticket for learning how to tune & if you blow it up while learning you still have the pipe & header in your arsenal for future motors.Last I looked you could bet a RB piston sleeve & rod for $125 on sale.