Should be blue with a white stripe.
PM me your email address and I'll send a copy of the wiring colours (admittedly from around 1982, but the colours don't change).
Above colour code assumes Morgan have followed the colour charts of course - test the lead before fitting. Do fit a relay (via a switch - your dip/main column switch will not be strong enough to cope with the current the drive lamps will need).
Cheers,