Rob,
My experience with the Tufo sealant is that above 90 or 100 psi the stuff starts squirting out of the cut in the tire. The Vittoria Pit Stop is better, but not by much ( maybe 120psi ?). YMMV. What I would do with those old Clements is send them down to Tire Alert in Florida and have new tubes sewn in. As an extra added bonus you get a new base tape. Or you can do the repair (retube, resew yourself). About Tufo tape. The regular tape is formulated for cyclocross applications and should not be used for road type applications (that's according to Tufo North America). I used it on one pair of GP4 rims here in Texas and it was an awful mess to remove. That experience alone convinced me that good old Mastik-One was the way to go.
Marty Eison
Frisco, Texas