Originally Posted by KyleDallas

Here is a practical application for the use of different rockers on
a 327/350hp L-79.

You are surfing Ebay and notice a set of Vortec L31 #885 heads
with a Buy it Now price of $300.00 complete with valves, rockers,
etc. .....
You buy the heads and order a set of 1.7 ratio rockers... you leave
your L-79 cam intact... but instead of giving you .447/.447 lift...
you are now getting .506/.506 lift... making the most of your head
flow while not digging into the block. L31's go for $300 to $350 a
pair pretty routinely.

If you wanted to to step up a little over the L31's... you could
order the 185cc Bowtie Vortecs for $554 a pair bare from GM Performance Parts Direct.... or the Dart IE Platinums 200cc port for $660.00 a pair bare from Competition Products.... and use the same
rocker ratio trick with your stock L-79 cam.

Intake flow for 492's with stock 1.5's
198cfm at .400 lift

Intake for L31's with 1.7 rockers
239cfm at .500 lift

Intake for Bowite Vortec 185cc with 1.7's
251cfm at .500 lift

Intake for Dart IE Platinum 200cc with 1.7's
274cfm at .500 lift

all figures using the stock L-79 cam...

Originally Posted by aworks

AFR and Dart heads have raised rails. In other words where the valve cover bolts on they are .5 higher than stock GM heads. Thats why roller rockers will fit under stock valve covers when using aftermarket heads. Most will not clear with stock heads. Sometimes double gaskets work or just buy spacers.