When you leave Lake Bistineau, take 163 to 164 east to US371 north, I-20 west, then exit back onto US371 north. Stay on US371 north to I-30 E. Take exit 98B US270 west toward Hot Springs. Turn left to merge onto US270 West toward Glenwood/Mt Ida. (do NOT take Bus70). Take exit 1 toward Mt Ida. At the end of the ramp, bear to the right to stay on US270 West (Albert Pike Rd). About 2 miles, at the traffic light (McDonalds on left corner). Turn right on Hwy 227 (Mountain Pine Rd) which will take you to Lake Ouachita State Park.
Note: follow the US270 directions to the letter as it's a bit confusing.
Also do NOT take Hwy 7 from I-30. Although it's an OK road, 270 is better.