One thing that helps is to make the shroud two piece. Trying to wrestle a one piece shroud on a car that's tight, (or later work on a water pump) is a pain. I usually make them from inexpensive galvanized sheetmetal, and either split them top/bottom, or side to side.
The local sheetmetal shops will usually bend up a rectangle and then bend the edges up 90 degree for $10. Then I figure center for the fan and cut the shroud in half. After that I cut the hole for the fan in each half. I have the rectangle made a couple inches larger in the direction I want to split, and then I can overlap the two halves when I install it. The bend on the edges I have made long enough to allow for mounting and spacing off the radiator.
I mount mine with tabs that I pop rivet or bolt to the shroud. I hate those plastic ties that mount the shroud or fan to the radiator core, as I've seen the cores damaged trying to push them through, or later as they vibrate or sag. I mount my fan to the shroud, or radiator, but not to the core. My Austin's fan is mounted to the frontend, and tilts open with the frontend. I can't run the engine a long time with it open, as there's no cooling then.