Freddy333, as usual is the voice of reason, but $1000!? Confused, since obtaining a 1575 either serviced, or that you have serviced puts you in the $1500 neighborhood just for the movement.
I can comment based on some recent similar dilemmas.
I have a 1680 project sitting idle. In short, ALL GEN parts but the Yuki mid-case. However, my serviced 1575, originally for this project, is sitting pretty in my Gen 1603 Datejust that was to be the donor. My dilemma is do I part out the Gen 1603 -> Build the 1680 Super Franken -> Re-power the 1603 with ETA, and end up going from GEN + REP to Super Franken + Franken. Back to Freddy333's point. I can buy a white 1680 for under $5000, or even a Red as low as $9000. Running the numbers I would be pushing $2500 into the project.
Fast forward to my recent Rail 1665. It is by no means a "Super" Franken, but a "Solid" Franken. I have to say, "in person" it rocks and is giving me huge satisfaction. I feel it has enough of an RSC Service look to be plausible. Even this project has cost me close to $800 based on Gen parts, and donor watches used to make it. (I should be able to lower its build cost once I resell some of the unused donor parts down the road.
Back to the matter at hand, and building on Freddy333's comments and a conversation I had recently with Ubi. You need to come up with a % percentage of Gen Cost -vs- Franken Build that you are comfortable with. Where this really plays out is when you start thinking about Daytona's, rare 1665s, etc.
Example, lets say you are willing to spend up to 10% "Gen" pricing to build your "Super-Super" Franken.
Gen DRSD = $50,000. @ 10% "willingness" your project budget would be $5000.
Gen White 1680 = $5000. @ 10% = $500. (See my dilemma from above)
Set a budget / plan.
No real answer I am afraid, but hopefully this will give you something to ponder.