mounting a slant 6

I'm putting a 1953 dodge truck on a 89 Dakota frame that had a v6 magnum. I'm looking to use a slant 6 engine. when measuring the pan looks like it will fit but my crossmember looks to far back. Would I have to mount the engine to the crossmember or could I mount it a few inches in front of it. Which means the cross member would sit in the middle of the engine
Author: martin53