Thanks for your help.
I was able to use your work and the error codes produced by my attempts to come up with an updated boards.txt entry.
On my mac the path to the boards.txt is:
Arduino.app/Contents/Resources/Java/hardware/arduino/avr/boards.txt
Here is the entry:
##############################################################
atmega328t.name=ATMega 328 - USBTinyISP
atmega328t.upload.maximum_size=32768
atmega328t.upload.speed=57600
atmega328t.upload.tool=arduino:usbtinyisp
atmega328t.bootloader.low_fuses=0xFF
atmega328t.bootloader.high_fuses=0xDD
atmega328t.bootloader.extended_fuses=0x05
atmega328t.bootloader.path=atmega
atmega328t.bootloader.file=ATmegaBOOT_168_atmega328.hex
atmega328t.bootloader.unlock_bits=0x3F
atmega328t.bootloader.lock_bits=0x0F
atmega328t.build.mcu=atmega328p
atmega328t.build.f_cpu=16000000L
atmega328t.build.core=arduino
atmega328t.build.variant=standard
##############################################################
Thanks again for your help.
Regards Tim