78/79 broncos did not come with a big block (460) option. Will pay 100$ for proof of VIN that shows it factory installed (seriously!!!). That does not mean that certain dealers or certain people who worked for ford did not get one dropped in on the sly. It was/is a simple swap as the 351m/400 uses the same big block bellhousing as the 460 (not the FE pattern, BTW).
As for comfort, hands down the 78/79 rides better stock or lifted than an EB. The much longer wheelbase and higher weight all but assures it. I own a 79 with 2" lift and 35 AT's and a 70 with 3.5 lift (deaver/cage combo that "should" ride like a dream!!) and 33 AP's. The 70 is not even in the 79's league. I wish it was, because I think the EB is cooler to drive, but it's just not.
Ease of working on?? They are both real close in platforms, the fullsize parts are somewhat heavier, but are also better with factory 205 and either C6 or 435 trans (some had T-18 also). Axles are a hair better in 78/79, but comparable in strength to the size/weight of vehicle, IMO.
For a 500$ 78/79, you will get a rusted out POS, but it will still be much nicer than a 500$ EB.
Desirability, still goes no contest to the EB's, but it's easy to say the 78/79 broncos are the most desirable full size sport utes made in the last 30 years (collector wise). Look at the number of EB's you see in music vids or movies. Don't see any 78/79's.
Harder to find parts for? NO WAY!!!!!!!! Shares 80%+ of parts with either 73-79 (most body parts) and 80-83 (engine/rear/trans parts) with F150's, the best selling vehicle ever.
78/79's had more available creature comfort features std or optional than early broncos. Cruise, factory AM/FM/CB, in dash air (or high output heater with dash vents and larger heater core), push bar, fog lights, power rear window, captains chairs, foldable rear seat, tilt, lighted visors, map lights, map pockets, slider rear windows, locking hood release, fulltime 4WD with center diff lock, int wipers, lockable center console, sport steering wheel, quad fronts shocks, alum wheels, optional 32 gallon fuel tank, towing mirrors).
Don't think any of that was avail on EB's (not sure on pushbar or alum wheels).