Vidarbha lead by 292 runs at stumps after bowling out the hosts, who resumed from 242 for seven, for 289 to garner a small yet important first innings lead of 37 runs.
But that slender nature of the lead mandated that Vidarbha should bat well in their second dig and Shorey (59, 114b, 5x4) took over that job, making a patient half-century.
Shorey's prudence and Danish Malewar's aggression (42, 63b, 7x4) sat together well and helped Vidarbha overcome a jittery start.
The visitors had lost opener Atharva Taide and one-down Aman Mokhade while adding just 24.
But the third wicket alliance worth 64 between Shorey and Malewar eased Vidarbha's nerves before the latter got out.
Shorey built another 68 runs for the fourth wicket alongside first-innings centurion Rathod (56, 75b, 3x4) as Vidarbha went past the 150-mark and the overall lead also neared 200.
However, Swapnil Singh ousted Shorey to keep Uttarakhand afloat.
But Akshay Karnewar struck an unbeaten 30 off 55 balls to take Vidarbha past the 250-mark as they stretched their lead close to 300.
Skipper Akshay Wadkar (16 batting) is giving company to him at close and Vidarbha will be eager to add a few more runs to the lead on the final day to keep their position and points safe.
Earlier, a four-wicket haul by veteran off-spinner Akshay Wakhare (4/62) helped Vidarbha earn a first innings lead.
Brief scores:
In Dehradun: Vidarbha 326 and 255/6 in 67 overs (Dhruv Shorey 59, Danish Malewar 42, Yash Rathod 56; Swapnil Singh 2/74) vs Uttarakhand: 289 all out in 107.2 overs (Ravikumar Samarth 119; Akshay Wakhare 4/62).