To understand the Morgan NM 454, you sort of need to understand that Morgan started out building racing sailboats and for much of its existence built what were essentially two different boat lines; one that was solely race boats and the other that was solely cruisers. And many companies that build race boats, each of the race boats that Morgan built represented a snapshot of the most extreme race boats of that day and age. The Morgan NM 454, like its smaller sistership, the Morgan 36-4/6, began as "we are no joking, we are going grand prix racing boats". The prototypes were extreme examples of IOR race boats of that era, stripped out, with complex internal structural systems, deep draft fin keels, big fragile rigs and deep fin keels and spade rudders. Nelso Merek was about as good an IOR rule beating design team as there was at that moment in time. Rumor had it that the hulls for those original, we are not joking boats were not built at Morgan, but were built at a custom yard in order maintain the required level of quality control required for a race boat.
But like any IOR race boat, the were quickly made obsolete by changes in the IOR rule and some advances in yacht design that happened concurrently. Morgan had a lot of money in the molds and decided to produce production versions of the boat. The production versions were constructed in three levels of finish from a close to an out and out racer to a very nicely finished centerboard cruiser. There was a club level race boat that fell in between. The production versions were greatly compromised from the few original full blown race versions having heavier hulls, less ballast and stability, smaller rigs, poorer internal framing structure and build quality. But in their day they offered reasonably good performance. That performance came with all of the serious problems associated with an IOR design of that era. This is especially true of the Centerboard versions which had substantially higher center of gravities than the deeper fin keel full race versions.
These are very physical and unforgiving boats to sail. They were designed to be sailed large crews perched on the rail to keep the boat upright. The rig depended on huge headsails, big sail inventories, and frequent sail changes because they lacked the stability to carry those headsails across a broad wind range. The result is that the keel versions are a great boat to mess around on in moderate conditions, or a half way decent club racer, but these are not a great boat for light air or offshore sailing.
Two big negatives on the boats is that the large crossover bridge deck on the non-racing versions are a real safety hazard and make it difficult to rig a dodger and still be able to get below. The other big negative is that the centerboard versions have a really awful motion, tending to roll a lot. Depending on when the boat was built in the cycle there are reportedly a broad range of quality issues, some of which may have been addressed by previous owners by now some are just a part of the boat that would be tough to deal with.
you might want to check with Catalina; they bought at least some of the Morgan catalog, molds, etc. They have the old Morgan 44 brochure available on their website, so maybe they have some stuff relating to your boat too.
I have looked on the Catalina webpage before. The 454 like some of Morgan's more limited production race boats does not appear on the list of boats that they have literature on.