Scott,

I've got my LNC2 cowl pins running through the firewall and aft to the
instrument panel.  They have a loop at the panel for a finger pull and
safety wire.  Header tank interference was not a factor.  The guide
tubes on the aft side of the firewall are simply nyla flow tubing with
an occasional 2 Bid and foam hard point.  The first piano hinge loop is
on the lower cowl.  This allows pin alignment.  Then as the upper cowl
is set in place the pins are relatively easy to get started down the
holes.  I suggest running the pins in and out many times with an
electric drill before looping the end.  They'll loosen up but it does
take awhile.  I really like them.

Another great installation I saw was on Jerry Knapp's 360.  His pins do
extract from the front at the air intake ring.  The have silver soldered
fittings (hex head) which screw nicely into the outboard internal edge
of the ring (the female fitting).  A guy in CA made the weld and they've
got pretty good life.  There is a pretty stiff turn at the beginning
obviously.

Need a photo?  Let me know.  I should be home this weekend.

Larry