If you use infinite fuel, it will be easy to get rocket to the high orbit of earth or other planet's orbit but if you do not use infinite fuel, you can go 30-40 kilometres high.
It is just inefficient but if it reached LEO then it's a decent SSTO self-launch station. I don't see a problem even though some things can drastically improve. Like Aero.
The REAL PROBLEM is the useless size tanks on the Titans. Attach it directly to the station and let it remain part of it. Also, you can probably use 2 clipped Frontiers on the core.