Add spaces to the directory listing to pad out to the size. New code is:

 4600 REM
 4610 DF=0:REM START AT FIRST ENTRY
 4620 IF MA(DF+2)<>0 THEN GOSUB 4400:REM PRINT CURRENT DIR ENTRY
 4630 DF=DF+32:REM ADVANCE TO NEXT DIR ENTRY
 4640 IF DF<512 GOTO 4620:REM BLOCKS ARE 512 BYTES
 4660 RETURN
 4800 REM POKE LBA, CHECK STAT, READ BLOCK TO MA()
 4810 GOSUB 3800:REM POKE LBA VALS
 4820 GOSUB 2200:REM CHECK CARD INIT STATUS
 4830 GOSUB 2400:REM READ IN BLOCK
 4840 RETURN

Result is better 

*** DIRECTORY ***
SYSTEM~1.      0
HOCKEY.BAS     8377
HORSER~1.BAS   3014
HURKLE.BAS     1390
KINEMA.BAS     813
KING.BAS       8950
LABYRI~1.BAS   4988