I can't see how four blades kicks up more dust any more than it cuts better.
I say why spend twice as much to change the blades.
You can save the blades and bolts for when the remaining two eventually need replacing. Double your mileage out of the four.

Those two mowers look great as a pairing. No way they look 35 years apart.

Ahh, if only victa had kept producing the thumblatch catcher series, they would be in better shape today!