Jack,
I don't think you need a roller cam...they're nice, but it's not necessary.
If you go with the comp adjustable roller tip rockers, they'll fit under
any stock covers.
If you go with the harland sharp full rollers...I've heard you need a
spacer or use 2 gaskets per side...(don't quote me)
As far as cam manufacturers...
I'd try
www.bulletcams.com
I've heard plenty of good things about these guys.
They specialize in custom grinds and they know Olds.
I've also heard a custom grind isn't as expensive as you'd think.
PLUS...it's made to be exactly what you want...keep your brakes
AND get as much cam as you need.
As far as comp goes...I'll hold my tongue.
You're most of the way there...13.5 with a cam that size, in a car that heavy is very respectable. A better cam and Drag Radials and your in the 12's.
-Pete