This is a very common setup in some bracket race circles, as I have seen several of them.
Never looked at the details, but I think a motor plate is the easiest way to mount stuff.
Having just rebuilt my first 350 Chevy, after 40 years of nothing but small block Fords, I don't think it is any cheaper than doing a 302 or 351w Ford. Certainly not any easier. Even finding decent 350 blocks to build is harder and more expensive than finding 302's from my recent experience. Parts interchange between the years is also not any better than Fords.
Oil pans and timing sets differ, oil pickup is a pita, fuel pump drive is odd, stock heads have press in studs, chamber sizes are not good for much compression, cranks and rear seals differ, HEI's seem more difficult to work on than Durasparks, balancers and timing pointers vary widely, intake bolts leak, and header bolt/sparkplug access is painful. It will take the same parts, good heads, well matched cam, intake, carb and ignition, as well as trans, and cost and such to get decent performance from the Chebby as with a native Ford motor. Just figured out you cannot change the 350 cam without dropping the oilpan!
I would also note that the car is not going to be popular with either the Chevy or the Ford crowd, especially for resale.
To each his own, it can be done, but I can't see why.
Just adding my .02.