Jacking, footings and welds...

I have a 1979 manufactured home my family and I are remodeling. We have noticed that the end of the home which is an open porch appeared to be sloping dorm the center down to the outside edges.

When we uncovered the end main I-Beam we think we discovered why. In the center of tat large metal beam is a weld with a crack halfway down it's center.

My plan is to jack up the outside edges and place 8x8 posts under each end and the center on 30 inch concrete footings, as well as rewelding the crack once the beam is straight.

We would appreciate any suggestions or critique of our planned approach. I have included two pics showing the location of the failing weld and the intended placement of the posts.

Questions we have is: can the beam be welded? Are the 8x8 posts big enough to do the job? Are the footings going to work? The frost line is thirty inches and we would use rebar in the footings.

Thanks

Dave