1960s yamaha p125a prop?

have a old yam outboard,previous owner lost the prop off.got her running well, but its a anti clockwise spin.i managed to souce a prop with the same shaft diameter but its a clockwise spin.i cut agroove in theback of the prop for the pin, thinking that if i turn it round it would do, wrong! so the question is can i use the outboard sensibly using reverse to go forwards ,and forwards for reverse. as its very old unit, its not worth spending a lot on .hope for some help on this problem, many thanks