The 2001-2004 Bullitt wheels have a +30mm offset and a 5.72" backspace. If you are trying to get to a vintage-friendly 4.5-4.75" backspace, then you want a 1" to 1.25" spacer (adapter, actually). Personally, I think you might find a better fit with the 4.72" backspace that the 1" adapter provides.
The 2005+ Bullitt wheels have a 6.29" backspace (+45mm offset) and need either a 1.25 or 1.5" adapter to fit most vintage cars.
You might have trouble with clearance if you have some aftermarket uppers (GW comes to mind), as these are made with a different shape than stock.
That is the exact problem I ran into on my '66 coupe. I have the GW uppers and never did get the sn-95 bullits to fit. I believe I spaced them out 1 inch and they still hit. I then sold the wheels. I have wondered if the 1.25" spacers would do the trick...
Tracy,
What is the rim closest to hitting? Also, what suspension do you have on your 65? I've always loved your car, even with the lawn chair... I'd think that with a 1" spacer, you'd be farther from the UCA nose, but IDK. I have a set of 1" adapters and 1996 GT 17" wheels. Maybe I'll do a mockup on my stock UCA suspended 66 (w/lowered UCA) tomorrow or Friday and report back. They have the same 5.72" backspace that the pre-2005 Bullitts have.
Daniel