We raced a 260Z in the 24 Hours of LeMons last October. Three hours into the race, the tired old R180 died a terrible death. I had a spare S30 R200, halfshafts, and a driveshaft stored at my dad's house about an hour away from the track, so we swapped the R180 for the R200 in the middle of the night in the dark and cold. The R200 uses different half shafts, different driveshaft, and different mustache bar. As long as you can get those parts, you can do the swap.
Unfortunately for us, my only R200 mustache bar was at my house 4 hours from the track. Our solution was to cut and weld the R180 mustache bar and make it work for the R200. The total job including travelling to get the parts and fabricating a mustache bar at 3am, took about 12 hours. The working conditions were less than ideal. We had been awake for days, it was cold and rainy, and the car was on a car trailer to keep it out of the deep mud.
We were back on the track by 8am and finished the last 4 hours of the race.