You mentioned Small Bore:
There are several types of Small Bore matches out there. The most popular now days is the NRA or CMP Light Rifle Matches. These are geared for the rifles most of us have in our closet. You don't need expensive equipment, if fact, you're not allowed to use heavy coats 'n such.
In this case your Marlin will work quite well. If you out grow (shooting wise) your marlin, the most popular, light super accurate rifle for these matches is the CZ 452s.
Then we have the NRA Small Bore and ISU (International Small Bore). This shooting can get pricy. This is where your Anschutz and similar rifles come in. They have several configurations. Standard and Prone Rifles. They can get well over $1000, plus hundreds more for the the equipment, shooting coats, pants, mats, gloves, etc, etc.
Then you have 22 Rimfire Metallic Silhouette. These matches have different classes but you can start out with your marlin and see how far you want to advance.
What I would recommend, is you use your Marlin rifle in the NRA or CMP Light rifle matches and see where you want to go from there. You have your rifle, all you need to get started is lots of ammo. Most Marlins I've seen are fairly accurate. Do most of your practice off hand (standing). Thats where matches are won or lost.
I'm a huge fan of the NRA/CMP light rifle competitions. They are designed that anyone can be competitiive. You don't need a lot of money, most people already have some sort of 22. Light rifle is just that, about 8 lbs so you arn't trying to compete with Heavy expensive match rifles. Its about the skill of the shooter, not how much money you can aford to dump in a sport.
If one out grows his closet 22, then there is the CZ 452s. They cost about $350 but they are supper accurate. The CMP GSM (Garand, Springfield, vintage Miliatry rifle) games also include the Light or Sporting Rifle events. When I went to the CMP Master Instructors' course, there were several instructors that delt with light rifle shooting. I (being a high power shooter) inquired as to the best rifle. Just about every one recommended the CZ 452.
Like I said, that is the high end. I sitll recommend starting with what you have on hand. And again, practice off hand or standing.
CPT USAR Ret
USAMU Sniper School Oct '78
Distinguished Rifle Badge 1071