The plans that I have are from a kit that
Lancair sold me back in 1991, which include a blueprint "Q" from the 320
kit dated 8/89 that pretty clearly show bolts through the longeron.
Sounds like the 320FB kits may have had some revision from what I
received.

Scott,

 

Here are some considerations for you to consider.

 

I was an early 320 hinged canopy builder and had to hand make the pockets in the header tank. I did make slightly taller longeron supports for the gas strut for a more positive over center hold-down of the canopy. 

 

The support has bolts thru the longeron, one below the longeron thru a fuselage hard point and one above the longeron thru the inside vertical of a multi-bid glass "U" bracket bonded to the longeron.  The outside vertical is used to seal the 1.5 inch long gap created by the canopy seal joggle in the fwd deck.  The forward deck (containing the header tank) is attached by the hinge pin method.

 

The canopy itself has skin extensions (inverted "U") that fit over and beyond the top of the longeron when the canopy is closed - the interior extension keeps the forward part of the canopy from being pulled outward during high speed flight by the negative pressure.  The exterior overlap keeps the rain out when parked. 

 

Additionally, I had to add a foam and uni-directional carbon stiffener to the canopy between the forward hinge attach points because the strong "squeeze" exerted by the gas struts forces the leading edge of the canopy to severly rub against the vertical part of the forward deck canopy seal joggle just before the canopy is closed.  I use teflon tape on the joggle to assist the slide between the parts.  Also, I added glass inverted small "u" receivers for the hinge on the underside of the forward deck where the hinges rest when the canopy is open.  These are padded with firm rubber to take the shock of a quickly opened canopy and the sides hold the open canopy more securely in a cross wind and to help reduce the adverse forces trying to rip the header tank from the forward deck. 

 

I have had two "hard" landings (at least) which were severe enough to bend the nose wheel forks but I never had a problem with the longeron area since there is so much flox used in the area where the longeron is drilled.  Flox that is used to fill in the area between the fuselage and the gas strut support bracket.

 

Good Luck.