Does anyone know the proper spacing between the cab and bed on a 92 F-150 SC 4x4?

I just replaced the "doggie box" (you'll have to see my gallery pics to know what I'm talking about ) bed that was on the truck when I bought it.

Couple of other questions:

1. I need 2 bed bolts that I'm missing; 2 front ones (oval shank). Where can I get these? I know most junkyards cut them.

2. How much paint will it take to cover '8 foot bed? Sides only, tailgate is good, spray in bedliner coming.

Thanks.