i found a 318 hooked up to a 904 in a 84 ram here locally. my question is will that 318 mate to my 435 with out any issues??

 

yes it should as long as you have the correct bellhousing (smallblock mopar).
The only other problem you may encounter is that an input bushing may not have been installed in the crank shaft. check to see if that bushing is instaslled and if the crank is drilled for it.