I used a hack saw blade to cut around the old Horiz. stabilizer

H. Stab gone. New stab. is thicker, so opening must be enlarged

Initial check of level of the new H. Stab.

For more precise levelling I used a water level. Here I compare wing tips. This is very accurate if the water is free of bubbles.

Here is a closeup of the meniscus. The tubng is 3/8" so the water level is abt .1: high. That is an error of about 1.5 arcmnutes.

Here is the right wing tip. A little high as well, so I guess the mis-level of the wings is actually about 1 arcminute.

Crosscheck of level between the longerons

yes, level

Used box-sealing tape as a release on bottom of Hstab. Built a support of dry micro below Hstab. Did this twice, checking end to end level of Hstab and incidence angle.

Then layed up 4 bids from inside of fuselage, around curve on micro and draped them outside. Then placed the Hstab in place carefully aligned it and pressed bids up against release tape for a custom molded support.

Removed the Hstab

Trimmed the rough edges of pedastal to about 1" width. Removed release tape from Hstab, sanded and degreased Hstab.and cradle.Tested the alignment of the tail. Applied 3-4 mm of Hysol to cradle and bulkhead below tail. Carefully supported Hstab and slid it into place, then set it down on hysol.

Placed the water level at the leading edge of the Hstab to check the angle of incidence

Trailing edge is 5-6 mm high. Water level tubes were about 450 mm apart so incidence slope is -5.5/450 or -0.7 plus or minus 0.1 degree.

Shot from 30 feet away. Elevation of camera is set so a slight gap is seen between the wing and the two tail tips. The tail angle in roll matches the wing to 1 mm, better than 0.1 degree.

Here is the check of the alignment in Yaw. The black line on the floor is parallel to the trailing edge to about 0.05 degree. I made the line by first dropping a plumb line from the bottom rudder hinge to the floor, and one from the centerline on the firewall. I marked that centerline, then made a perdendicular to it using a steel carpenters square.

Checking the leveling of the Hstab using the water level.

This is the right side...looks good.