How much cam? And who's cam? Your cam usually dictates the exhaust recommendation. I'm using a 284 extreme energy from CompCams (240/245@0.050 with .503/.510 lift). Comp says headers (1 3/4" Hedman w/ 3" collector), more stall converter for an auto (2800 stall for my T400) and don't forget to use an intake manifold that matches your cam RPM range (Victor Jr for me). If you use a single plane intake, make sure your carburetor (if that is what you're using) works with that manifold. The cam manufacturer will also mention how accessories will be affected by the cam. Comp say accessories will be affected, but according to Chevrolet, base time is set near 20 degrees (with the vacuum advance disconnected) and I'm using a dbl pumper holley with 4 corner idle. So vacuum is at or near 16kpa at 950rpm. Review the timing curve in the Chevrolet power manual and taylor your timing curve to that and set base timing per their recommendation. If you are using fast burn heads, there is probably a different timing curve. I have an older 383 with 23 degree AFR heads, so I use the early engine timing curve.