Sweet 240z but needs lots of work, what's it worth?

So I am trying to help my elderly father trim his holdings. Prime on the list: 1971 Datsun 240z, manual transmission, Series I. Its been neglected since 1978, but is not badly rusted![IMG_20191119_083803794_HDR|375x500]. Was in a fender bender in 78, not driven since. Has replacement body parts: hood, fenders, bumper, and many more parts. Engine wasn’t drained that first winter, so there is freeze damage, but another engine is a part of the package, it needs a valve job, I think, tho. Plus an extra head in apparently good condition. My problem: how to establish a value for the car and all those great parts?? Can you advise, please?