66-67 hardtop vs 4 door seat bottom difference

I have a 67 Belvedere 4 door...and decided to put buckets in it. A couple years back I ran across some 66 Coronet RT buckets on CL and they had brand new black RT seat covers that came with them. It was an awesome deal and now I have newly covered Coronet RT buckets. Unfortunately I have a 67 Belvedere back seat that doesn't come close to matching in the pattern. I've come this far...might as well go ahead and make them match....even though it will not be the correct pattern for a Belvedere. Unfortunately, no one makes a Coronet RT rear seat cover to fit a 4 door seat bottom.

My options to get the back seat to match.

1. Buy hardtop seat cover and have an upholstery shop modify the bottom to fit my 4 door seat frame. About $300 for the cover and another $300 to modify and install
2. Go all custom at an upholstery shop....probably more time and more money with a chance the material and pattern don't match as well (according to the shop)
3. Buy a hardtop seat bottom and do the install myself

The problem with option 3 is that I don't know how much different the seat bottom radius is. If it is too sharp, there will be very little leg room when entering or leaving the back seat. Also the sides may be exposed and visible.

Does anyone have a 2 door hardtop 66-67 b body seat they could send me some pictures and dimensions for reference? I'm thinking option 1 will be my best way to go, but I also need the 2 door seat radius to determine how much the 4 door radius will cut into the pleat pattern.

PM me if you can help.
Thanks
Dave

4. Buy the fabric needed from Legendary or SMS and have a upholstery shop make and install them.