too big a pump can cause problems for a filter but if they are matched it should not be that much of a problem. 300 lbs of sand does not sound like a hugh filer so you should be ok. You might also need some pea gravel to cover the laterals.
post the make/model number of the pump and of the filter (they are not the same) If this is a skidpack (both on one one base) then there would be a make/model for that also possibly.