Any saiyan elite, the royal saiyans, are able to control their oozaru forms. Vegeta explains this pretty well by his own words. It is the lower class saiyans, like Goku and Raditz that do not control their oozaru forms.
Also, you rate the avergae saiyan as having a strength of 27. That is way low. Even as a child, Goku could lift far more than that.
Consider a strength of 27 is a max lift 1,040 pounds.
Goku as a child could easily throw a tank. Consider the Red Ribbon tanks to be equivalent to a panzer, which weighed in at about 75 tons. Now consider that to throw it, it would have to be a medium load to Goku. The tank would weigh 150,000 pounds. That is a strength score of about 69 as a child, power level approximately 175.
Scale that to Raditz, power level about 2,000, meaning Raditz was about 12 times stronger than Goku, meaning he could throw about 1,800,000 pounds. That is a strength score of about 85.
Saiyans are amazingly strong creatures, eventually surpassing planet destroying levels, especially considering the mere shockwaves caused by super saiyan Goku's punches crumbled mountains.
Also, in Dragonball, improving one's ki can be learned, but one can be born with higher ki without any training at all.