How much tuning pin in pinblock?

[David Skolnik]

Hello -
I'm rebuilding a Knabe, which had a 1 1'2" thick block (thicker in 
bass)  and plate thickness at webbing which ranges from .22" to 
.35".  At what seems like reasonable coil distance from plate, there 
is only about 1" of pin in the block (using 2 3/8" pins).  How much 
of pin should ideally be in block?  or is that an answerable question?
Thanks

David Skolnik