I just helped a friend setup a Henry Frontier for 22 Silhouette and thought I'd share the info:

If you change the rear sight to a Williams peep you'll need to also change the front site to a Lyman 17 Globe to get the right sighting height. Here's the parts you'll need. The prices from Brownell's are cheaper than what I paid for my setup.
ppkny

1. Williams rear dovetail peep sight ( fits the dovetail no drilling)
Williams FP-GR-TK Mfg# 9685 Brownells 962-201-606WB $71.99
http://www.brownells.com/rifle-parts/si ... =962201606

2. Lyman Globe front site (simple remove original and replace with this)
Lyman Model 17AUG .584 height Mfg# 3171080 Brownells 539-017-532WB $39.99
http://www.brownells.com/rifle-parts/si ... =539017532

3. You don't need to replace the gib screw but this one will let you adjust without a screw driver.
Williams Target elevation gib lock screw
Williams Gib lock Screw Mfg# 61613 Brownells 962-000-079WB $8.99
http://www.brownells.com/gunsmith-tools ... =962000079

Now that's a nice looking rear sight set-up.

Putting one together for my son tonight, same parts I was told to order... Looks good!

What is the rear aperture you used? What kind of tape (?) did you use to mark? I just got a new Williams and it has the directional arrows, but really like to mark zeros like you have.
Thanks for sharing

chuck

it looks like a merrit rear aperture.

The rear aperture is a Merit Corp Lens Disc with a B Jones lense in it. I use a .25 diopter in my Henry and a .38 diopter in my 357 Rossi and 30-30 Win. because of the longer sight distance. This all depends on what condition your eye sight is. Being older It's difficult to get the front sight in focus without an aid.

http://www.meritcorporation.com/products.html
http://www.bjonessights.com/index.html

The tape is Avery permanent mailing labels cut from any of their stock label sheets.