I had the engine completly submerged in my syncro pick up but it was a diesel, only needed a good blob of vasaline on the power wire to the fuel cutoff switch! (oh and air intake/ gearbox breathers raised up higher) Had no other mods apart from a 2" lift and 16" mud tyres That truck was great fun 8)
As long as you keep it runing and the air intake is sealed to above the water line its fine. When i worked for the MOD we use to convert land rovers for the sas that could go up to the roof line with a person stood up through the sunroof in fact they could go deeper but the driver complained that they could not breath
