In from work tonight and decided to sort seat subframes (drivers mainly so I can turn the car round!). Used some wood blocks straight edge and a mallet to knock them both straight and was a bit shocked at how easy they were to bend!. I had planned on making a box section square to weld on top, or as some had suggested take the OEM rails out and remake the seat mounts and weld them to the body. I've ended up using some 3mm thick angle iron (can't remember the word for it!), and cut sections to fit around the subframes, all ready to weld up in the morning. I figured that I've used the same for my sill reinforcement and I can jack the car up from the middle of the sill (only did it once by accident!) so supporting 80kg should be fine.. I'll put 2 support legs on the front corners as well so instead of 3 points it will have 5.
All welded up yesterday, done drivers side but need more angle iron for passenger side. At least I can get car turned round and passenger floor stripped.