Welcome to the board!
Please save a 914.
Now on to your question... it really depends on what you mean by
QUOTE
relatively rust free
and how good you are at welding.
Do you know or have you read about all the areas for rust?
There are some "standard" areas such as battery boxes and engine shelf pockets. Right longitudinals and both jack posts seem to be the worst. If your rear taillight seals were bad then the back 1/2 of the trunk floor will need to be replaced. If your rear window wasn't sealed then the rear 1/2 of your floor pan will be gone. Sail panels can be bad at the bottom where the factory foam was applied. Same goes for the metal above the rear taillights. Cowls can rust and they seem to go around the seals between the fender and cowl... look closely before you waltz in.
A good 914 can be relatively inexpensive at $5-6k.
A bad 914 can be relatively expensive at $500.00