So, just for giggles, what is going to consume this file? It seems odd that you have to delimit the file AND make the columns fixed length.

So to answer the question, I'm not 100% how SSIS will treat padded spaces. I would recommend trying to pad the spaces in your source component query (using REPLICATE) and also use CAST to change the data types from varchar to char before it enters the data flow's pipeline. Another option may be to use a Derived Column transformation in your data flow to use an expression to pad the spaces. I'm just not sure how SSIS will react when it writes the file.

I'll test a little and reply, but I thought that I'd give you a head start on where to look also.