Can you find out which Ford diesel it is? Around that time a variety were marinised by a few different companies. Some parts
may be very hard to get.
Same may apply to the transmission. Can you find the model number?
My experience with an old Ford engine
transmission was that repair/rebuild was not economically feasible. I went with a new engine transmission.
If the hull
is really corroded you may need to have it filled in places with weld metal and reblasted. If the corrosion
is really, really bad it may be better to pass on the boat.
As to the cost of abrasive blasting, it depends where you are. Some areas, like Sydney
have essentially banned abrasive blasting, others are more accommodating. Best to look up abrasive blasters in your local yellow pages and let your fingers do the walking. You could also ask round your local slipways.