I think 140 is very realistic. The reality is that the US has no way to prevent Iran from closing the strait. There's a reason all the carrier groups are hanging out far away from Iranian shores, and sorties into Iran are being done from ground bases right now. But let's for a moment assume that the US was capable of doing escorts through the strait. That oil would worth more than gold by the time it got through. Just imagine the number of interceptors they'd have to use up on each pass, with every one costing millions. There's simply no economically viable way to do this.