Long was held to a field goal and two free throws in the second quarter while Renz scored six points.
Leading 30-23 at the start of the third quarter, the Ironmen went on a 10-0 run as Selinsgrove did not record its first points of the quarter until Nikki Krebs made a pair of free throws with 2:49 left. Long had the only bucket of the quarter which came with eight seconds remaining.
Danville outscore Selinsgrove 14-5 in the quarter.
"That was a good battle and Laura Long is a good player," said Danville coach Steve Moser. "The last time we played Selinsgrove (Jan. 12, a 57-40 Danville win), Long was banged up a little but. We really didn't get to see the real Laura Long that night.
"I thought early, she got real good position down too deep and so the adjustment we made was to put Amber on her man-to-man and the other four girls were going to play zone."
After the adjustment, Long was held to nine points in the second half.
In Danville's last outing, Moser felt the girls did not play a complete game in the one-point loss to Milton on Feb. 1.
Tuesday was a different story.
"Your goal is to win each quarter," Moser added. "We won three and tied one, but I thought our effort was much, much better. We knew that Selinsgrove is a physical club and they've been playing better lately. We knew coming in this was going to be a war. When they came out on all cylinders and I'm thinking, 'uh-oh, this is going to be a 32-minute job.' But we shot very well and we had very few turnovers."
Erica Heath and Keeley each scored 11 points for Danville, which hit the 60-point mark for the sixth time this season. They are 6-0 when doing so.