I haven't seen any issues associated with using filler on the street. Wall integrity is greatly enhanced by using some form of filler IMHO.
This 393 was filled so the grout is level with the water pump outlets when levelled. Motor has gone 10.9 in a 3600 lb car and is driven on the street all the time. Runs a CSR pump and alloy radiator. Running a standard volume oil pump as well and the pressures look good.