Need to replace Cab Mount Supports...help

[airbrushguy]

Beginning winter project...
Went under 1971 C10 LWB Stepside, all four cab supports are rusted out. Bought new ones and would like to replace with cab still on frame.
Where and how should I lift cab to give me room to replace/weld supports in?
Rockers are going to be replaced and a small section of floor at edge of rocker area.
Was hoping I could fix floor and make it solid before I decided whether I wanted to take a foot out of frame to shorten LWB.
Am I attempting something someone has done before or should I rethink plan?
I do/did not want this to become another project that grows larger at each part. The truck is going to get a V8 in place of 6 and the body/paint will remain as is with a little nod to aging it to become a tribute to my dad's service station with aged lettering etc.
Please only respond with helpful advice, I really don't want to sink a ton of $$$ into this as I have with all my other vehicles...help me avoid that. I am quite qualified as a welder, mechanic and very determined.
Thanks in advance