You may not have this option where you live, but if I had to make the glue line cut you're describing in a slab that thick, I would load it up in my truck and take it across town to a local shop that has a Schelling beam saw. They would charge about $20 to change the blade over and make that single cut, to a laser line, but it would be quick, and most importantly, clean. I would also bring the new slab to have it cut to width, perfectly parallel. Those two extra cuts might add a little more machine time, maybe five minutes.
I realize this solution doesn't provide you with the excuse to buy a TS 75, or any other tools. Sorry.