Wednesday's clash in New Plymouth, the ninth meeting between Taranaki and their British and Irish visitors, should see a ferocious forward battle, with Munster duo John Hayes and Donncha O'Callaghan (pictured above) both handed another chance to impress with their second caps, and first starts on New Zealand soil.
"We're envisaging a tough game," said McGeechan, who led the last Lions tour to All-Black country in 1993.
"Taranaki played some very good rugby last year but we know that we'll learn more by facing good teams such as these. We're under no illusions about the test we'll face.
"Defeat would halt our momentum but if we're ultimately successful, then we know that this game will have been useful.
"Like any New Zealand side, Taranaki's basic work and technical work is excellent. They will challenge our basics from the word go.
"It is no doubt more of a challenge than playing some of the provincial sides you get in Australia. It is a far greater test especially in the early part of the tour - for any side that faces the Lions, it is full on throughout. It is the biggest game some of their players will play in."
Llanelli Scarlets coach Jenkins added, ahead of the sold-out Yarrow Stadium meeting: "Taranaki's pack is well drilled, well coached, well organised. It has a very good scrum and a very efficient and complicated lineout system.
"Their approach to the contact is as a good as it gets, and they're well aware of body position and intensity.
"For people to suggest that the game down here hasn't got a forward approach is not correct."
Veteran prop Gordon Slater will also line out, twelve years on from packing down against England's Jason Leonard on the Lions tour. Out wide, Samoan international wing Sailosi Tagicakibau has made a remarkable recovery to start against the men-in-red, having broken his leg just over five weeks ago, whilst playing for Super 12 outfit the Waikato Chiefs.
1908: Taranaki 5 Lions 01930: Taranaki 7 Lions 231950: Taranaki 3 Lions 251959: Taranaki 3 Lions 151966: Taranaki 9 Lions 121971: Taranaki 9 Lions 141977: Taranaki 13 Lions 211993: Taranaki 25 Lions 49