I would like to see Sea Dragon 1st stage + Orion combination. It balances nicely the level of nuclear fallout from Orion Engine and the excessive weight of the chemical rocket booster.
To make it really work, need a completely re-usable Sea Dragon 1st stage (if you do not want to discard a machine as large as naval heavy cruiser after each flight, which is not an option for any administration).
The real problem for Sea Dragon is the 360 MN (37 kt) thrust engine. Regenerative or radiative cooling of heavily-built combustion chamber is not going to work, especially if you imagine all protruding vanes necessary to eliminate combustion instabilities in huge chamber volume. It basically mean rhenium (with technology level of 1963) chamber and nozzle throat. Something like 200 tonnes of rhenium per vehicle, or 4-5 years of OTL world rhenium production per vehicle.
Therefore, building "Sea Dragon" would be an epic deed. Like "colony ship" in "civilization" or "c-evo" games (if you built it, you automatically assumed to be world ruler, new calendar starts from the day of the 1st flight "Space Era Year 1, Dragonember 1st"). And losing each Sea Dragon would be a major world disaster, enough to introduce a special national holiday along with Christmas. ("Dragon Mourning day, Orionember 26th").
More realistically about political climate..Sea Dragon requires united world. Without unification, any project of such complexity would be cancelled in favor of more bombers and ICBMs.
P.S. Rombus would have ~1/2 payload of Sea Dragon 1st stage for ~4 times lower launch mass - thanks to LOX/LH2 engines. Unfortunately, i cannot see realistically how the Rombus can be effectively reused. Dropping LH2 tanks and itself in 4 widely spaced lots is not simplifying re-assembly (see the sad economics lessons of Space Shuttle boosters re-use). Need to transport and re-mate huge blocks, instead of just refueling.
P.P.S. Integrating Sea Dragon with Orion would be also a huge challenge. Need to re-land Sea Dragon on launch site just on top of huge transporter (may be after refueling at touchdown site if different from launch site), vent residual propellants, use transporter to move Sea Dragon to maintenance hangar, mate Orion, load nuclear bombs, move assembled vehicle to launch pad, offload from transporter, connect the refueling pipes, load propellants, disconnect refueling pipes - and do not forget wrenches in the main gimbal!