why not just reuse the 318 exhaust manifolds? unless this is going to be a performance build, the small amount you lose performance wise isn't worth farting around with manifolds - if you do want the extra performance, get a set of headers on it - why fight with the 360 manifolds - use something that'll bolt in. The 904 should be a good option - just a flex plate to deal with - way easier and cheaper than having a driveshaft reworked. Are you wanting to just get the Dart running again or do you have loftier ideas for the car - what you do is really all about what you want out of the car...