[Aubrey N Bruneau]

Been there, and done all that, Greg ! On my old 64 Pontiac convertible, that's almost exactly how my heads were done. I sold that car to build this one !
One thing is for absolutely sure... there is no possible way on earth that I could achieve .100" piston to valve on the exhaust, without taking 20 degrees dutration out of the cam, and milling the piston a WHOLE lot !
It's all good... really. and the trouble is that it never really does "nose over"... especially down at sea level in Mission. Exhaust valve is always good... but probably due to a much more gentle lobe. No bounce.
It's just the damn intake.
BTW, the track... sea level ( as opposed to dyno )... yes, that was a lesson !

Alan, much longer valves create a new problem in geometry... particularly on the exhaust valve, because of the angles of the rocker stud in relation to the valve. Not ideal at all.
Not to mention, I already have my valves sunk into the heads at least ..050" deeper than stock ( piston to valve is a real problem )... so longer valves would be way up there.

Good news is, yes, I can fit 1.55 spring. That was my old combination.
Results were the same.
Maybe I should mention that my heads, at .510" lift, flowed 288 / 212.
Certainly not the potential of a large port BBC.

The right retainers and keepers ?
yup.... been chasing that one for a while !