CPPA Slant six to RB motor mounts and CPPA headers...

I have a pair of CPPA slant six to RB motor mounts as well as the CPPA underchassis headers I am installing in my 69 Dart. Has anyone used these parts and what was there experience with them? Will the engine sit in the same location it would if an B/RB k frame was used or will it be further forward or back and require transmission crossmember modification? Also, How well do the CPPA headers work in this application with a four speed? This question comes after installing a four speed floor hump in the stock location but before installing the ballstud bracket on the frame. Am I wrong to assume everything will line up with these mounts? Thaks for any input!