Wendy, welcome to 'Mud.
That is a very nice looking FJ55. One can see why you want to keep it as original as possible. Unfortunately, the best way to do this is to do it yourself. Fortunately, you have the knowledge of the ages here on 'Mud.
We ('Mud) are much, much better at teaching you how...
How set are you on having an "original" FJ55 engine? FJ55s came with 3 different engines, the F engine, Late F engine and the 2F engine. The 2F engine started in 1975, your Pig looks to be pre-1975. It would be easier to find a rebuilt 2F than an F engine. Probably harder yet to find a Late F...