....There are other factors that have lead me to use the 14b as my rearend (full floater, huge R/P, 1.5" shafts, cheap detroit, 5.38s gears now available, easy to rebuild).
Also, a lot of people take the weight factor as a bad thing when in reality the heavier axle will improve droop,
and lower the COG of the rig. You just have to make sure the chassis and suspension are up to the task of keeping it under control.
What you said is true, but you can't assume you will get 1.5" shafts in a 14 bolt. There are lots of different models, many have necked down shafts that are only 1.3x. The spindle OD, wheel bearings and seals are the same in the 14 bolt, D70, and D60. The real advantage of the 14 bolt (besides strength) is if you get it from a pick-and-pull type wrecking yard they usually have a cheap flat rate for any rear axle, $100 - $150. Then if you keep looking long enough you can find one with stock 4.56 gears, 1.5" shafts and 63 or 67 inch with. You can spool it by welding it, or buy a detroit for $350 or so. The detroit installs in the stock carrier that's why it is cheaper than one for a D60 or D44.
If you are not running tires > 38", and you are going to pay to regear to 5.38, and install a full locker like an ARB, then the 14 bolt doesn't really have any advantage over a D60, especially cost wise. And then you have a heavier axle and less ground clearance. While heavy axles do place the weight down low where you want it, it also means more unsprung weight wich results in a really rough riding vehicle on the pavement.
Also, your choices for a matching 8 lug front axle are limitted to a Ford 3/4 ton 8 lug D44, or a Ford D60.
If you are not planning on running a D60 front, then the 14 bolt rear makes even less sense. If you do plan on a D60 front then you will probably want a Ford high pinion D60 from a 1978-1979 F350. These are becoming rare and go for a premium price even for a rebuildable junk yard axle. They have the required driver's drop diff, open knuckles, king pins, 35/30 spline shafts, disc brakes, and enough space for coil spring perches.. There are other axles that can be adapted but they are less desireable and usually require more work. The cost of alloy shafts, u-joints, knuckles, high steer arms, gears, and lockers for a D60 is significantly more than for a D44 so plan ahead.
I think the best way to plan a build is to decide on tire size and build accordingly. 35's will require quite a bit of additional strengthening of steering components, and unibody stiffening. 38's and up will require more extensive mods to the body, especially in the rear to open up the wheel wells, as well as some form of hydro steering and probably hydro assist brakes, at that piont a cage or exo will probably be needed to keep the the unibody from tearing itself apart. All these things should be considered and budgeted for before you purchase anything.