I am currently running a SSBC front disk conversion on my 68. I want to upgrade to larger wheels (15 rally-17 ARE Hopsters) and want to go with the C5,C4 or baer (13inch) upgrade also. My question is will the front wheel backspacing differ between the 2 disk setups? I want to upgrade my wheels now and do the disks later this summer. I have read on this board that on a 17x8 wheel I would need approx 4.5-5.0 in backspace for the disks. Any help would be appreciated.

Not that I could help you but you might be able to help me... What size SSBC are you currently running? With what size wheel - 15"?

Zless67, I currently have the SSBC 11 inch front disk set up with 15x7 Wheel Vintique Rally wheels. Let me know if you need anymore info.

130fe, thanks for the response. I'm about to buy 17" Wheel Vintique rally's(68 series) to go over a 12" . I've heard of some issues with the big calipers SSBC provides in relationship with the wheel vintiques??? Anyone hear of this?

I have the 13" Baer Track brakes on my 67 Firebird convertible and my Centerline wheels are 17x8 with 5" backspace. I could run another inch either way and be fine. By the way, several 16" wheels fit my Baers. If you have not decided on your wheels, check the Wheel Deals section at the Centerline site, they have a large selection of 17" wheels for around $100 each. Thats where I got mine.
17" wheels (http://images.cardomain.com/member_images/4/web/412000-412999/412680_1_full.jpg)
Wheel Deals (http://www.centerlinewheels.com/wheel_deals.php)