A full pressure 235 will run those speeds (and faster) just fine with the right gearing. However, the stock neither the stock trans nor a 4 speed will help that. The best fixes will be either a rear gear change (like the Patricks 3.55 gearset) or a transmission with an overdrive final gear, which would require swapping to an open driveline. Larger diameter tires will hep in that area as well.
A few things you do want to make sure of if you're going to run those speeds, Brakes must be in good shape, steering and suspension components (including tires) must also be in top condition.
