I thought that you had said that the unit of time is the second. That's how I interpreted "quarter = 60". If you don't want this nor any other related basis such as 120 divisions or 240 divisions, why did you say "quarter = 60" at all ?

Yes the tempo is quarter = 60, but this doesn't mean that I want the chords with durations in rounded seconds. What I was thinking is to make a transposition from a duration (say 3,57s) into musical figures, thats why is easy for me to use quarter = 60. Another thing is that the interpreter will have a pulsation basis so (s)he can read the music more easily, but it will not sound like regular pulsations,
Sorry if I wasn't clear enough, I think maybe 1/100 of a second is a good time basis, I can and will need to make some approximations of the musical figures, so the interpreter won't have to lose his/her hair studying a 48s section.

Caio Barros