The problem isn’t the sample time, I have no issues loading longer >1min files. (you can use the start pos param move through the entire file.) The problem seems to be that the envelope release wont go longer than 3000ms. This seems fixable. I will look into it today.
edit: So, this seems like a pretty easy change, a few lines in ack.lua and Engine_Ack.sc. Unfortunately, none of this code is mine. I wonder if @jah is open to extending the volume release time a bit?