I shot the 2700 matches a fair bit in the '60s and 70s. Drifted away only because the places I was at didn't host those matches, and I wasn't into postal shoots.
Having said that, welcome to a very interesting sport. As far as a spectator sport goes, it is about as boring as it gets. The participants, however, have enough mental and physical challenges to make it a lifetime sport!
The advice to build strength in your shooting arm is excellent. The advice of old timers was that the 1911 demands a firm grip to shoot well. My own experience was that the grip was tight enough that the rib pattern on the front and back of the grip transferred to my hand and fingers. Developing that kind of strength and endurance may mean that you will probably want to find one of those exercise aids that help strengthen the hand.
Some folks went so far as to hang weights from the magazine for dry-fire practice. Others poured lead into an old magazine. You'd be amazed by how much and extra pound or so during dry-fire improves one's endurance during slow-fire.
Trigger squeeze will become important. The out-of-box 1911 tends to have a very heavy trigger and occasionally a bit of creep. A better trigger or gunsmith work to improve yours would be the second investment, with the first being the sights you choose to use.
After that a match barrel and bushing would be useful. Before that step, I would advise that you shoot the Buckmark enough in practice sessions to get a feel at how good your shooting might be with a properly tuned 1911.
Another trick available now but not 40 years ago is to have a laser boresight in the barrel of your pistol during dry fire. Work your trigger squeeze to the point where the only movement seen in the spot on the target or wall is that caused by the trigger fall. That won't be more than an inch or so at 25 yards.
The challenges of Bullseye rapid fire are overrated. There is time to single-action a revolver and to squeeze the trigger during the five shot sequence and to get 8 or 9 shots out of the ten ring. A semiauto is even easier.
Last -- by all means use low velocity semi-wadcutter ammunition or load your own. Use the 230 gr "Ball" ammunition only when match rules require it. The ammunition accuracy will be more or less the same, but precisely controlling the pistol when shooting ball ammo is a lot more challenging!