"The largest solid rocket motors ever built were Aerojet's three 260 inch monolithic solid motors cast in Florida.[18] Motors 260 SL-1 and SL-2 were 261 inches in diameter, 80 ft 8in long, weighed 1,858,300 pounds and had a maximum thrust of 3.5M pounds. Burn duration was two minutes. The nozzle throat was large enough to walk through standing up. The motor was capable of serving as a 1-to-1 replacement for the 8-engine Saturn 1 liquid-propellant first stage but was never used as such. Motor 260 SL-3 was of similar length and weight but had a maximum 5.4M pounds thrust and a shorter duration."
and
"Between Sept. 25, 1965 and June 17, 1967, three static test firings [of the AJ-260 rocket] were done. SL-1 was fired at night, and the flame was clearly visible from Miami 50 km away, producing over 3 million pounds of thrust. SL-2 was fired with similar success and relatively uneventful. SL-3, the third and what would be the final test rocket, used a partially submerged nozzle and produced 2,670,000 kgf thrust, making it the largest solid-fuel rocket ever."
For more see: https://en.m.wikipedia.org/wiki/Aerojet#Florida_facility_and...
There are parts of the F-1 engine that would be difficult to exactly replicate because while the engineering specs are known the exact fabrication processes weren't all documented. An exact workalike could be made for those parts that fit the specification without a problem. That new engine would need to be entirely requalified for use.
The F-1 is big and expensive and rebuilding them has long been outside of NASA's budget. If they were going to rebuild the F-1 it would be the same expense and effort to just design an entirely new engine.
This is why, for instance, the SLS is using the SSME as its first stage engines. It's a known system with a long and successful (the engine itself) flight history. It's been iterated upon and is well understood.
The design philosophy of rockets has also changed from the 60s when the Saturn was designed. Solid fuel boosters were not considered useful for Saturn but have been proven since then and have a long flight history. There's also the SpaceX/Soyuz model of an array of smaller/simpler engines. A small number of monster engines is just not needed like it was for Saturn.
The expense of the F-1 and the lack of real need has kept NASA from using them, not some loss of technology. The guidance systems...are a long long solved technology. Modern guidance systems are better than the Apollo and Saturn systems by orders of magnitude. They're far smaller which allows redundancy and still lower weight than old systems.
Since Saturn NASA has launched successful probes to every planet in the solar system and several dwarf-planets, landed several extremely long lived rovers on Mars, launched hundreds of satellites, over a hundred Shuttle missions, and assembled one of the most complex machines ever in orbit.
What's sad is the mistaken belief that Apollo was some pinnacle of capability and technological prowess for NASA.