I have a pair of 17” Ultra Shield Spec Miata aluminum seats that will fit nicely into a 914 and plenty of room. You can fabricate brackets to fit stock sliders or purchase floor side mounts or after market sliders.
One seat has been taken out of the box to check for fitment, the other is still in the box in plastic. Both seats come with seat covers. The sets sold for $253 + Taxes each. I will sell as a pair only for $325 plus shipping. I also have 2 pair of MOMO steel side mount brackets 14”L X 6” H X 2” W base for $75. Plus Shipping…………………….. To view the seat Google Ultra Shield Spec Miata Item Code 607200 seat and 607201 cover, 31 lbs for 77573.Thanks for looking Mike