I'm new to the forum and just noticed this thread... I don't know if you still need an answer to this question, but I have some info. I have a 1995 tree 1050 also and you will need a bare minimun of 108". 12' would be great but you can get by with 108" with the cable carriers against the ceiling. As far as the concrete thickness i'm not sure. I was't the original owner of my shop.
P.S. I've started a thread about my spindle drive problems please help if you have any info.