Shareef O'Neal is ALMOST ready to hit the hardwood again ... the UCLA star tells TMZ Sports he's just a month and a half away from a return to the court!!!

"I feel great," he says.

Shareef underwent heart surgery to correct an irregularity back in December ... and his post-op pictures showed just how serious the procedure really was.

But, when we got the 19-year-old leaving Staples Center on Wednesday night ... he was in good spirits -- and tells us his first workouts since the operation are just DAYS away.