Ricardo,
Replacing floor pans in an exsisting built Speedster is possible but not a "shade tree" at home job.
On a scale of 1 to 10 scale I would rate it as an 8.
This really needs to be done on a chassis style lift.
I did do a pan replacement on a Speedster in my home shop with the Speedster jacked and blocked up approx 22" from the shop floor and that took 2 plus days with much cuss'in with no room to work and trying jockey a pan around under the car was at times, a near impossibility.
The second time I did a pan R&I, I upgraded the venue and off I went with a case of Coors Lite as bait for free after hours lift time good bs session and an extra set of hands at a friends body shop, we knocked that job out in less than 7 hours...Just in time for a midnight tapping of the now cold case...I did the shortening of the pans in the car as it was easier to work with the smaller cut down sections when working with the body on the chassis . Also spend the extra bucks and buy OEM German pans and not skimp on a thin gauge Mexican/Brazil pan set....Per Tim "Tool-Time "Allen ...measure twice cut once.
Alan M.