look, i don't know what the situation is but homie seems to just want to go against the grain and get a little different with it, which is fine. i like different. different is cool.
but 360 crank in a 318 is just GOBS of money in machine work: cut the mains on the crank, skim down the...
360 main journals are bigger than 318, so you'll need to cut those down (and ideally heat treat the crank after, or not). you'll also need to trim some of the counterweights to clear the pistons-- which will need to be custom. though you can run stock low compression 318 pistons they'll wind up...
your math here is a little wonky.
reman 5.2 long blocks are about 2500, hong kong phooey intake is 150, re-use your carb. you'll need a new oil pan & pick up but that's pickles.
so you'd probably be all in at about 3K
or roll some dice on something like this...
don't use the 273 heads on the mag motor. yes, it can be done but it's going backward.
i'd skip trying to repair them and go straight to a set of remans or really, right into a set of aftermarket alumn units.