Sealing old HVAC vents

My old HVAC system was in the crawlspace. My new system is in the attic. The HVAC crew removed the old ductwork in the crawlspace, but left the registers that cut through the floor. When the work was done there was a hole wide open to the crawlspace, so I stuffed the registers full of batt insulation and then covered it with spray foam.

Is there a better way to seal this up, short of patching the floor? There are some minor gaps between the edge of the registers and the cut into the floor that still allow some crawlspace smells to come up into the living space.