Can I do this to my seat?

I would like to tilt the high backed seats in my '69 rearward slightly to give me more head clearance and a better driving position and am wondering if I can do either of these things.

1. When the seat is tilted forward (for access to the rear seat) there are two rubber pads visible on the rear edge of the bottom seat cushion. If I remember correctly, the seat back 'stops' contact these two pads. Can I remove them and shave off a little material to allow the seat back to tilt slightly rearward?

2. Can I elongate the rear seat attachment holes upward to allow the seat to sit down further in the back? Is there any clearance to the floor under the seat? If I can do this, about how much? I would weld up the old holes so the seat does not suddenly tilt forward during a hard stop...

I know there is a weld in floor that can be put in to lower the seat but I am not interested in tearing up the floor just yet. I want to investigate these 'easy' fixes first.

Any suggestions are appreciated.
THANKS!!!

For some reason I was thinking that the front seat attachments were on a vertical wall not a horizontal one... I'm sure you are correct, I have not looked at it in awhile.