>  The 1000ms figure here is quite arbitrary.

Why not measure how long it takes to evaluate the similar expression:

    t := [ 100 timesRepeat: [ 33 printStringBase: 2 ] ] timeToRun

and then use the result t as an upper-bound to the execution time of
evaluating [ 33 printStringBase: 1 ] once? You probably have to play a
bit with the factor to get meaningful results.

Cheers,
Lukas

-- 
Lukas Renggli
http://www.lukas-renggli.ch