Tables in legend

I need to create a legend for a simple scatter plot in the following
format.

 This is Blah1  number1 number2
 This is Blah2  number3 number4
 .
 .
 .
 This is Blah6  number11        number12

I looked up these help pages and found the following solution.
lStr<-c(Blah1, Blah2,....Blah6, number 1, number2, ...number12)
legend(x="topright",lStr,ncol=3)

So this creates the tabular format I am looking for. But the width of
each column is matched to the width of the longest column. So the legend
now looks like this:

 This is Blah1                  number1                 number2
 This is Blah2                  number3                 number4
 .
 .
 .
 This is Blah6                  number11                        number12


And thus, I have the legend occupying most part of the top half of my
plot. I was wondering if there is any way to fit in the legend compactly
or even better to format the width of columns 2 and 3 in the legend and
remove the blank spaces between them. I have tried rounding off the
number values to 3 digits with no luck.

I hope this is not too ambitious to ask.

Thanks in advance!
Aparna