June, you have 1500 hours in type, so that would be about 750 touchdowns. You most likely would get about half or something just short of 400 impacts. Now through in something over 40 simulator affairs and you now have a lot of experience. By now you should be getting all most all on the centerline. What is the problem, could be a whole combination of seat height, where are you looking, arm rest, no arm rest, etc... I'd start with seat height, I've seen lots of pilots just sitting to low. Then, where are you looking during the flare? Hopefully still looking toward the end of the runway and horizon. Have had a few who started looking right over the nose and could not pick up the left or right drift.
The 73 is a great airplane and easy of fly, maybe you are overthinking the problem.