Fan shroud questions.

Hi Y'all,

I have finally gotten my 18" flexalite fan, and Shaguar XJ6 fan clutch. This gives me 1/2" spacing back from my aluminum radiator. I will still be needing a shroud. I plan on making my own out of spot welded sheet steel. Heres the questions

How far should the fan be out of the shroud. I am assuming half in / half out of the shroud.

How much spacing from the blade tips to the shroud. I am assuming 1/2" to 3/4"
(i am using polyurethane spool mounts)

Am i correct on these figures and assumptions?

Thanks in advance
Matt