I havent been able to look at the car yet but I was wondering if you could make some mounts that bolt to the factory holes, just move the seat back a couple inches.
Don't know about any brackets but I suppose you could drill new holes back about 2 inches and use plugs for the old ones. That would be quick and simple.
The angle will change, maybe, you need to put 1/8" rounded plate under, for washers, not fender washers.You may have to make/find spacers, due to moving them. I had to on aftermarket seats being moved.
My frend was 6 foot 9 and he got it to where he could fit in the 70 Dart ok enough. He put some blocks only onder the front ege of the seat to kick it back so his head would clear the roof that and with the seat all the way back he would fit it there.