383 in 68 Dodge Dart? new build

I'm going 383 4 speed in my 68. I traded a smallblock bellhousing for a BB. I have a stash of A body 4 speeds. 2 - 8 3/4 A body rears, TTI headers, and a few autos, should I get tired of shifting gears.
You already found a 383 and 2 transes, so you already have a headstart. You can use B body headers with your autos. You can get away with an A body 8 1/4 rear, or even go with a B body rear. You would need to change offset on rear rims, and move spring pearches. The radiator out of a 6 cylinder Gremlin will work and have the bottom hose connect on the driver side, unless you are looking at the 71 2BBL cast crank 383 (water pump outlet on the pass side.).

Having a 318 in a 68 makes me think you may already have an 8 3/8. Do the gears slide out the front or back of the rearend? If the gears slide out the front, stroke a small block, and it will bolt right in with pretty close to no mods. You may need to beef the trans a little if it's a 904.