Hemi barracuda

Having a 1966 426 for thirty years finally going to install in my 1968 barracuda. Many questions along the way but the one that I can not find info on is cutting the right inner fender for clearance for the engine head . Anyone know where you can find this info ?
Back when Hurst did them , they just clearance them w/ a big hammer, looked like h---.
You could always cut the thing out and figure it out after installing the engine. You`ll more than likely have it in and out more than once.
Offset mastercyl., k frame shims, flatten firewall to floorboard pinch seam etc---------