ARLINGTON HEIGHTS, Ill. – Trainer Larry Rivelli hit a milestone on Memorial Day weekend by winning his 1,000th race, and the horses who got him to that numeral of note are noteworthy in their own right. At Canterbury Park on Monday, Richies Sweetheart scored an impressive 3 1/4-length win over males in the $75,000 Honor the Hero Stakes. The 5-year-old mare, returning from a freshening, earned a career-best 97 Beyer Speed Figure. The mare’s regular rider, E.T. Baird, knew she was flying on the Canterbury grass course. “E.T. said that was the best race she’d run,” Rivelli said. “She wasn’t stopping. I think the older she gets, the better she gets. She was kind of a nervous type before, and she’s settling down.” Richies Sweetheart already has earned more than $500,000 while winning half of her 28 races. She won the $200,000 Turf Amazon last September at Parx Racing, and big-money turf sprints like that mainly are clustered in the late summer and fall. That means Richies Sweetheart probably will have a relatively quiet summer, and her connections are weighing whether to try to swoop into what they figure to be a relatively easy spot June 11, the Isaac Murphy Stakes for Illinois-breds over Arlington’s Polytrack, or wait for the $75,000 Brandywine Stakes on July 19 at Indiana Grand, a race Richies Sweetheart won last year. On Saturday at Arlington, Rivelli unveiled a promising 2-year-old filly first-time starter named Shackin Up, who won a 4 1/2-furlong Polytrack maiden race by nearly nine lengths. By Shackleford, Shackin Up earned a 67 Beyer. She has no place to run for quite some time, with the $125,000 My Dear Stakes on July 23 at Woodbine a likely target, Rivelli said. On Monday at Arlington, the talented but too-frequently injured Good Bye Greg returned from a layoff of almost a year with a sharp two-length win in a high-end Polytrack allowance race that produced a 93 Beyer. The victory appeared to be aided by a speed-biased track, but Good Bye Greg showed that he still possesses brilliance, and Rivelli hopes to run him June 20 at Presque Isle in the $100,000 Karl Boyes Memorial over 5 1/2 furlongs on Tapeta. Rivelli said the three weekend winners are among a group of about 10 horses he plans to stable at Saratoga when the meet there begins in July.