It took a while as I haven’t been around very much nut my 1967 MGB GT finally has new (or old) seats installed. I documented the modification of the Miata seats here and while the installation took a little longer than I expected it was also much easier as I just used 7/16 inch bolts to bolt the seats directly to the floor. Originally I had planned on making adapter plates but found this wasn’t necessary.
The seats will be pulled out again when I deal with a small rust issue in the floorboards and I’ll document hole location better at that time. Here’s an image showing the idea anyway. As you can see the new holes are about 3 1/2 inches in front of the old holes. This is needed to clear the cross brace at the front of the car.
The Miata seats are a tight fit but they do fit and have good movement both forward and backwards. With this bolt pattern a person shorter or taller than I am would have ample leg room so it works well. I’m 5’9″ and the seat is located in the middle.
I think they look quite good although I know purists might not agree. The only item I don’t like is the colour but I would like to recover them anyway at some point. In the meantime I might try to dye them a darker black.