Kentucky Derby winner Sunny's Halo worked seven furlongs in an excellent time of 1:24 over a deep, muddy strip at Pimlico today, and his trainer was extremely optimistic that the Kentucky Derby winner would run in the Preakness Saturday despite a rash

"If you asked me what chance of us going Saturday, I'd have to say better than 75 percent," said trainer Dave Cross. " . . . I'm so glad I could get this work in today. I was concerned that the treatment we've been giving the colt would screw up his metabolism. His work today sure verifies that that hasn't happened. I feel so much better today than yesterday. He is eating and is full of himself.

"I believe we have it under control now. We should know something by Tuesday--that would be 72 hours after we started the new medication.

"The main thing is to keep it (the infection) away from the girth area," Cross said of the portion of the horse's body touched by saddle straps. "If if spreads to there, I'm dead." Various types of antibiotics had been tried after Cross consulted with three specialists and his own veterinarian.

In today's workout, Sunny's Halo broke from the seven-eighths pole on the clubhouse turn and worked back to the wire in fractions of 24 seconds for the quarter, 47 4/5 for the half and hit the six-furlong mark in 1:12. His exercise rider, Eric Fried, said, "He does it so smoothly. I didn't think he was going that fast."

Veteran Maryland trainer Dick Dutrow was more impressed. Dutrow, the nation's top trainer in 1975, said Sunny's Halo had "the best workout I've ever seen here (Pimlico) for seven furlongs."

A half-hour earlier, Dutrow's horse, Disarco's Rib, winner of the Woodlawn Stakes at Pimlico in his last start under Julie Krone, breezed seven furlongs in 1:31 3/5, running the last quarter in 24 1/5. "My horse is fit," Dutrow said. "That Derby winner reminds me of Seattle Slew. I have to talk to my colt's owners Wednesday. If he goes in Saturday's Preakness, Julie Krone will definitely ride him."

Dixieland Band, a question mark for the Preakness after his lackluster third in the Preakness Prep, was officially declared out of the Preakness by trainer Charlie Peoples this morning.