Think of the mileage with an OD 4 speed though...
Id say besides changing tire size, maybe down the line swap in the later OD trans. Otherwise leave it be.
Yeah that's the Mopar FMJ suspension and K frame. Pretty popular swap for hot rods I was told.
Ask for parts for a 1978 Lebaron and you'll get everything ya need.
You will need to find a donor car. 65-68 should be pretty much the same. 69-73 could maybe be modified to work, I think the leaf spring/shackle area is slightly different on the fuselage C bodies.
Car was rotten under the top. Probably had other issues too. Send it out with a Bang. No harm done. He had it listed for sale and guess who showed up with $?
30k is plenty if you are doing stuff yourself.
If you gotta pay a shop to build the engine and trans. Pay a shop to do the body work and paint. Etc. It's gonna eat your budget.