I would also be worried about an old carter carb under water...I do plan to eventually build a snorkel out of ABS pipe for my Jeep, but it is fuel injected. Not that I plan to cross water that deep, but mudholes are always deeper than you expect and I would like the peace of mind (and sometimes you have no choice but to do a water crossing to get to where you are going). Also driving through water that deep usually kills your engine fan and sometimes takes the radiator out with it, which is why I have an electric fan with a manual shut-off switch for deep water. Then there is the ignition system, that doesn't like water either but at least it won't crack your block like sucking in water through the intake can.