Whitehead also came third in a senior speed shear a few hours later at Stratford's Commercial Hotel.
Her only previous competition was when she came third in a senior lamb shearing final at the Southern Shears in England earlier this year, part of her shearing globetrotting which has so far also taken her to Italy and Australia.
Raised in Gore, Whitehead is just three weeks into her first North Island main shear season.
She is working for Whangamomona contractor Dean Herlihy while preparing for the record bid, which will be made with sometime-regular competition shearers Sarah Higgins, Amy Silcock and Natalya Rangiawha.
Mangamahu Valley shearer Simon Goss had an expected fifth senior win this season, finishing the eight sheep in 8min 56sec, two minutes a head quicker than Whitehead who was third to finish, concentrating on getting the quality and job to the standard she'll be wanting during the record in front of five judges appointed by the World Sheep Shearing Records in the Waihi-Pukawa woolshed near Turangi in January 23.
Goss won by more than 9pts from runner-up Kieran Devane, of Taihape.
Grainger and Fagan battled over the lead in the 15-sheep open final, with Grainger shearing by 12 seconds and with the better quality outside points winning by 2pts and regaining the title he had won at Stratford two years ago.
Daniel Biggs, also of Mangamahu, continued his winning form with an intermediate final by 2pts from Cory Barrowcliffe, of Piopio, with third place going to Phil Price, of Old Radnor in Powys, Wales, while Aam Jones, also from Wales, won the Junior final, by more than 8pts from runner-up Reghan Ngarotata, of Piopio.
RESULTS from the Taranaki Shears at the Stratford A and P Show on Saturday, November 30, 2019:
Open final (15 sheep): Mark Grainger (Te Kuiti) 13min 7sec, 44.35pts, 1; Jack Fagan (Te Kuiti) 13min 19sec, 46.35pts, 2; Kaleb Foote (Piopio) 13min 52sec, 52.7333pts, 3; Marshall Guy (Kaeo/Taumarunui) 12min 49sec, 55.3833pts, 4.
Senior final (8 sheep): Simon Goss (Mangamahu) 8min 56sec, 32.925pts, 1; Kieran Devane (Taihape) 11min 36sec, 42.3pts, 2; Wilson Weeks (Apiti) 10min 47sec, 42.475pts, 3; Megan Whitehead (Gore) 10min 57sec, 44.1pts, 4.
Intermediate final (6 sheep): Daniel Biggs (Mangamahu) 7min 58sec, 32.0667pts, 1; Cory Barrowcliffe (Piopio) 8min 36sec, 34.0667pts, 2; Phil Price (Wales) 8min 40sec, 39.1667pts, 3; Topia Barrowcliffe (Piopio) 9min 11sec, 39.8833pts, 4.
Junior final (4 sheep): Sam Jones (Wales) 8min 1sec, 32.05pts, 1; Reghan Ngarotata (Piopio) 8min 19sec, 40.45pts, 2; Heath Barnsdall (Piopio) 9min 24sec, 40.95pts, 3; Josh Hopkirk (Masterton) 7min 37sec, 44.1pts, 4.
Novice final (1 sheep): Josh Devane (Taihape) 5min 1sec, 33.05pts, 1; Fynn Redshaw (Urenui) 5min 56sec, 40.8pts, 2; Regan Lark (Tahora) 4min 4sec, 60.2pts, 3.
Teams (6 sheep): Jordan Contracting 1, 6min 46sec, 1; Jordan Contracting 2, 7min 10sec, 2; Kevin Harley, 7min 52sec, 3; Reece Munroe Shearing, 7min 53sec, 4; Dean Herlihy Shearing, 8min24sec, 5.