rear spring perch rust repair - advice needed

So besides the van's outer panel rust, I have this rust/rot issue that must be taken care of. The driver side rear leaf spring perch is rotting bad as well as the van floor it is attached to. I will include a few pics in this post as well.
My questions are: Do I just fabricate the exact same stock set up it had before (and still has on the passenger side)? Anything special I should do to fix the van floor that appears to be flexing due to the rusted perch coming though or just weld in a new replacement panel? If so, is there a specific gauge metal to look for on this overall project?
I have the basic tools, welder and the will to get this done but want to research and plan ahead to tackle this once and as efficient as possible.
ANY advice is appreciated. Thanks!!!
Here's the bottom shot:

and the upper/inside view:

Oh boy!!!....That's your frame that's rotten. That would certainly cause the floor to move. How bad is the rest of the frame. I no this can be fixed, but depending on the rest of the frame, you may need to make a section big enough to go from the rear bumper up past the front spring perches. Others that have done this will undoubtedly chime in. But I believe this can be fixed.

Yes that can be repaired. If that was mine I'd find a van to get a patch from and replace the floor and sub frame section. I hope the main frame is in better shape. That looks like the usual rust we find.

ok weve seen that done here before -its in our archives =?? somewhere?? with detailed pics - i hope the vanner that did that repair will chime in & direct us on that again. Seems like he cut out the rusted area & welded in some heavywall tubing -maybe rectangular stuff -same size as origional too. then reinforced the sides & top & bottom with add'l plates too. Good ol salted roads!!

Thanks guys. I hope the member you are talking about Twinpilot will jump in on this thread. If not, I have some ideas and I have been planning this out with some mechanical buddies of mine here.
The rest of the frames and subframes are very near perfect, but when they Ziebarted the bottom of the van, they missed this corner apparently. It is the rockers, inner panels of the rockers, and the door lowers that need attention after this perch.
Thanks for the input so far. Any other advice is welcome too.

That's the ticket ..I bought a 67 and when I looked up while it was on the rack the frame looked great..that sold me..... then when it was transported the spings came through the rear of the floor ..ouch. This might be a time to modify the rear suspension..What direction...I would think a perch connected to the frame would be smarter ?

seems the best would be to make a piece that fits inside the old frame rail?? then another that goes over that=rectangular tube-heavy wall stuff!! yet best advice is - take it to a good welder & ask his advice or get a welder to stop buy the van??  

frozintime wrote:That's the ticket ..I bought a 67 and when I looked up while it was on the rack the frame looked great..that sold me..... then when it was transported the spings came through the rear of the floor ..ouch. This might be a time to modify the rear suspension..What direction...I would think a perch connected to the frame would be smarter ?

I've rebuilt this whole section now. It isn't "stock" but it is built better and to last. Check out the new rebuild pictures in the Member's build section under my name. Oh and FrozinTime, where are you in Maine? There's a few of us vanners around here. I'm in Turner (near Auburn).