[Mart]

You have a non stock application. That means you have to use your ingenuity. You have to work from first principles, one piece at a time. As said, the hood is the start point. Align this to the cab. Drop a plumb line from the centre of the hood down at the front. Is it on the centre line of the chassis? No? Unbolt the cab and move it until it is.
That's a start.
Put the grille in place, aligned to the hood which now fits perfectly to the cowl, and on centre. Does the grille sit at the right height? No? raise or lower it until it looks right, then shim the cab so the hood fits perfectly again.

Then carry on with each panel until you get them all fitting as well as it is possible to get them. It may be that it is impossible to ever get them perfect. You have to keep going until the quality of the fit and finish matches the character of what you are building.

As soon as you drift from stock you have to take the responsibility for making it work.

Mart.