Bulkhead fitting

Having replaced my chassis for a galvanised one I'm now rebuilding, I fitted the bulkhead loosely awhile ago just so I could rebuild engine bay etc, does anyone know how to re-align the bulkhead, does it square up off chassis for example, how do I know how many spacing washers to put in between outrigger and bulkhead? Any help would be appreciated please, (only engine and bulkhead on rolling chassis at moment)

Leave it loosely fitted until rest of landy is fitted tub doors roof etc then fasten em all together loosely and align it all as you tighten everything up.

Thanks Redhand I appreciate the advice.