55.2-59 New seat how to support new mount safely

[Missyblue]

Pic isnt mine but is the style seat I have. I read before that I should add metal to brace the new bolt holes in the floor since they wont go in the original braced locations. But not sure how much...would.a 3 or 4 inch plate with each bolt be enough or.should I run a strap all the way from side to side? As in front to tail to hold both bolts. Or driver to passenger ? Debated making a mount so I could use original holes but it's a bit off so would be kinda awkward.