Thoughts on swapping a slant 6 with a 383

Originally my plan was to use my 360 block, which needs machine work. But considering costs and the difference, I still have interest in a 383 in my 69 dart. The motor would be basically all stock except maybe a cam.
-I need to know if I can keep my power steering
-Would manifolds fit better or headers
-Is there any clearance issues with the heater
I've been reading a lot about big block a body swaps but everyone's situation always seems different. Keep in mind I'm not asking for inquiry about which motor i should go for.
Thanks :)