Yes I see the reccess your refering to,but how did you install the bracket and roller you fabricated. did you simply reave the new cable, run it through the block from below then wigle the assembly into the recess, then attach to the CB.
If so I'd be concerned the assembly would drop down when you lower the CB.
Sorry for all the questions, the idea is a good one, just can't see in my mind how it's installed.
If you look at the dwg carefully you'll see a nut welded on the underside of the top of the bracket, (the one that captures the cable in the pulley) I drilled a hole in the keel slot for a bolt that goes thru this nut held with large washers on top and sealed. This bolt washer & nut along with the cable fitting on the back hold the bracket up in place. In 2 years of service there has been no issue with the bracket setup. (just the swagged fitting on the cable slipping off. You need to double up on that)