You use the tie-wraps (bundle-ties to us MEN) to set and stretch the new covers just right before clamping them down with the hard wire, silly girl. No upholstery background, eh pretty lady?
I'm scanning the remnants of the build-sheet and will send you a copy for analysis, since I know you are interested in that. The paper is falling apart as we speak! You were one that mentioned this story a long while back, but I didn't really believe it would be there. Most people think if you pull the seat out it'll pop out into your waiting arms. Not so. Gotta dig a little.
'68 428 HO M3 Monster, 4-on-the-floor! Need I say more?