I second the call to contact Stern for advice about what the state of sealed beams are.
If you're interested in a sealed beam format LED conversion, he is also the one to talk to. The trucklite Gen 2 LED lamps were always a good option. With GE selling off their lighting division to Tungsram a few years ago, I'm not aware of the state of tungsrams current version of those lamps, there may be better offerings now.
It was a couple of decades ago... but I swapped the sealed beams on a 1976 Holden Torana (round fixtures) with a pair of H4 Narva reflectors, I understand that you don't want to spend a lot of time/cash on a $400 Truck but pound-for-pound the improvement was literally night and day,, best money I ever spent IMHO, perhaps a pick-a-part wreckers would be a worthwhile trip?
If it's something you drive regularly why not invest in a safety feature?
It sounds like it is a beat up, 30 years old truck, lights from DS cost $170 each. definitely not cost effective solution. Stock sealed beams are 15 bucks each at any auto parts store.
I don't think there is any progress going on with sealed beams at this point, they are phased out long ago, for road vehicles. Except for led conversions, which are not that good if cheap, or if they are half decent, they are not much less than DS units.
I know vast majority of cars have 4 sealed beams, 2 outside for low, 2 inside for high beams, those sealed units have both filaments, i'd wire them the way so all 4 light up, for high or low, wire them straight from the battery, vis relays. You will also eliminate stock wiring resistance issues. Wont cost you much more. The whole thing can probably be done for around 100 bucks, that is if you need to buy stuff, if you already have wires, relays, then even less.