And using composite structure and tanks? Is possible, the Titan II used hypergolic propellants. And i've selected the LR-87-11 engine because -obviously- it's updated and that means more thrust.
It would be best do the math on this if your serious- nothing else would give a useful answer to your questions. Before we do anything else, or modify anything, let's first ground ourselves in the data for a stock Titan 2 first stage(all sourced from Wikipedia, by the way):
Masses
First stage dry mass: 4,319 kg
First stage wet mass: 121,200 kg
LR-87 mass: ~850 kg
Propellent mass: 116,881 kg
LR-87-5 specs
Thrust sea level:
956.5 kN 1913 kN
ISP sea level: 259 s
Thrust vacuum:
1096.8 kNs 2193.6 kN
ISP vacuum: 297 s
Now, we could get out the pad and pencil and do the math for finding the
Delta-v of a stock Titan 2 first stage the hard, rewarding way, or we could use a online calculator,
like this one. Since I chose to wimp out, the calculator gave me this result: 9930.41 m/s. I know from experience and book learning that a ascent to orbit, launching due east from the Cape will take about ~9000 m/s of delta-v, depending on how efficient I am, and how high I put my initial apogee; so there is some excess performance for payload/new structure.
Figure out what wings might mass, and add them to your dry mass(to keep with your original idea), or add the mass to both dry and total masses so you don't lose out on propellent. Play with the numbers, trying to ensure the modified vehicle can still make at least 9,000 m/2, and if you find something that you like, you can try using Spunik's CVEL Titans to fly it in Orbiter; if you encounter trouble setting up the scenario, I might be able to help you work it out.