Some of us haven't bought into the must have "Ford in a Ford" mantra...FYI, that's a SBC block in my underway '38 project Ford. If "some ***embly is required" on your project '38, you might want to change out that Corvair front suspension and brakes for a dropped axle set-up. My understanding is the claim to fame for the Corvair front suspension is that it bolts in with 6 bolts...so it should also be easy to remove. Feel free to check out the build thread in my signature line. It too has a dropped axle set-up.
Do what I did on Henrietta the '38 Ford pickup. Paint the small block Chevy the dark green color used on Ford flatheads. Put Ford emblems on the no-name valve covers. Make up a ****-and-bull story about the rare Ford experimental OHV engine.
I don't understand the Ford into Ford thinking. Engine swaps are at the core of hot rodding. Even GM got into the act. I distinctly remember that my brother's Buick Regal had a 301 Pontiac engine in it.
As far as the market I doubt that a Ford running gear swap will do much to enhance the value. Aside from the Corvair front end the GM stuff is pretty typical and fits well. If the o/p plans to only have it 3 to 5 years I would suggest finishing it up and enjoy it or sell it for a Ford powered ride you like better.