Rear end gear options with stock axle

[Oldgearz]

Ok I'm a new member, luckily Im getting to know this truck inside and out, since its a rolling resto. From the threads I've read sofar it looks like my standard gears should be 3.90. This is also pretty obvious since at 55 it feels like the engine is close to redline. My tires are stock size, 28"diameter. I ran the calculators on Richmond's site and determined best ratio to be able to do 75 comfortably would be 2.73. I'm looking to NOT spend a small fortune on this and keeping the Muncie 3spd HD because of the rarity and cool factor of it. How can I make this work with my existing axle or do I really need to swap out the whole darn rear end?