The Builder would change the whole frame In Order to accomodate the Travel length of a suspension fork ..

It can Be done but it wouldn't Be the same Bike Model ..

the 'Suspension Corrected' Rigid Fork has Longer Blades so the Head tube angle is not altered .

Tout Terrain Is a Builder, as Is Thorn, Making a Frame that can Do both as It is a Taller Off the Ground Head tube design . ..