Hi,
you can connect the LCD data bus directly to the 8051's data bus. but it is a good practice to buffer through a 74HCT245.follow the ckt below. a 2 input NAND gate will do
__________ /E
/WR--| | |
| /& |----| | | | |
/RD--| | | /& |----| /& |----E
| | | |
LCD_CS---------| |

/WR--------------------------------R/W

A0--------------------------------R/S

you can use the spare NAND to invert the /LCD_CS from the address decoder.
the /LCD_CS is memory mapped. if you are using '245, control the data direction by using /WR or /RD