Are chainring bolts alone strong enough?
I assume by 'ridge machined into the spider to hold the chainring centered' you mean the edge of the shoulders machined into the spider arms.

The edges are not there to position the chainring nor transmit torque. The chainring bolts do that. Remember the force transmitted to the chainrings by the bolts is perpendicular to a radial line drawn through the spider arm.
The chainring bolt holes in your spider need to be accurately positioned and sized to accept the bolts. I doubt laser cutting will achieve the required accuracy for the holes and these will need to be machined.