Ok, I'll jump in on this one, since I am looking for a project myself. First of all, it's worth as much as the buyer wants to pay.
That being said, other guidelines might be "What can it be parted out for" - "the hassle of parting it out".
If it is a correctly swapped over car, with v-8 running gear and brakes, driveshaft, interior and glass, AND the body is in above average condition compared to an unrestored Original V-8, I might give $500 for it. If I were really interested, I might go to $800. Just not much interest in v8 conversions as restoration candidates (especially with front drums). This is my opinion, you may feel differently.
That being said, other guidelines might be "What can it be parted out for" - "the hassle of parting it out".
If it is a correctly swapped over car, with v-8 running gear and brakes, driveshaft, interior and glass, AND the body is in above average condition compared to an unrestored Original V-8, I might give $500 for it. If I were really interested, I might go to $800. Just not much interest in v8 conversions as restoration candidates (especially with front drums). This is my opinion, you may feel differently.