Hello I will help you with your question,
If you want to use a real 400 crank you need to get the rod journals cut down to fit the rods and you can have it offset ground at the same time to get more stroke.
I suggest buying a stroker package to fit your block as the crank is already machined and ready to bolt in.
Please let me know how I can help you
i took a 400 crank out of this block tyhe problem is the rod journals are to narrow