Gidday all,
Two discharge blades on the 1963 Corvette will be adequate as that's what the mower is designed for.

I see the 1983 Victa Vortex is advertised as having a high velocity arch.

Eight angled fins on the blade disc and the arch generate the air flow.

A few examples of different blade designs ,see image.

Cheers
Max.

Attachments
Corvette.jpg (126.8 KB, 95 downloads)
Vortex.jpg (113.93 KB, 94 downloads)
Vortex 1.jpg (36.33 KB, 93 downloads)
Cutting Action.jpg (90.58 KB, 93 downloads)