I also have a 460 and I run a similar set up. My valve covers do have a baffle box, but I don't have two breathers I have a direct line from the carb to one cover... Also I already run 15-40.
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Sounds about right to me.. Just for reference, if you ever get a whole bunch of oil "up top" the valve cover without the breather can become quite pressurized and blow out the valve cover gasket... Making for a gnarly mess, not to mention a pretty scary smoke show.... If it works, leave it alone...
Just thought I would give the 4-1-1...
BTW, I really do not like the FOMOCO breather block under the carburetor, I just feel that it is wrong because you cannot see if something catastrophic is actually going on. Sort of like out of sight, out of mind.
They work pretty well on a car, way more vacuum to get it to clean up. On a jet, the crankcase pressure is "pushing" into the intake manifold. Just feels, again, wrong.
GT