recommendation on Grizzly Jointer

Personally I prefer the handwheel adjustments to lever adjustments. They both work fine, I just find the handwheels easier to set precisely.

No direct experience w/ either but either would be decent choice imo.

My catalog is a little out of date but it appears the G0490 is the G0586 w/ the spiral cutterhead instead of knives and the other chief difference between the two above is the parallelogram as opposed to the dovetailed ways design.

For a school shop I can see advantages in either -- the higher fence and parallelogram may be slight advantages for students but I'd think the prime choice between the two would be dictated by your experience w/ knife life and treatment and make the selection on which of those you think better for a longterm cost and maintenance issue.

The spiral head is about a $400 premium I imagine on initial cost, but you might get sufficiently longer life from the carbide inserts over HSS knives. But, if damage from "kids are kids" type vandalism has been a problem, the cost of the inserts could be more of an expense.

I'll withhold comment on bureaucratic budgetary policy... :)