There really are no clutch adjustments on a bugeye--there is a pedal position adjustment on the pedal box, but this would have to be pretty far off to cause the clutch to slip.
You might want to get under the car and look at the slave cylinder and pushrod--it should have a very little slack when the clutch pedal is not pressed. If it's very tight, maybe that could be the problem, but still I have a hard time imagining how that could happen. Main thing is to check all external possibilities before assuming that the clutch is bad. You don't want to pull the engine and then discover that it was unnecessary.
On the other hand, clutches do, alas, wear out. Fortunately, the parts aren't too expensive, especially if you shop around a bit.