I don't remember where I bought them, but these are them:
Amazon.com: Flexible Light Strip 300 SMD White LED Ribbon 5 Meter or 16 Feet By Ledwholesalers, 2026wh: Home Improvement
My fixtures are approx 5" x 18" and contained 2 florescent tubes. Between the tubes, under a reflector/cover are the ballast. I removed the cover and the ballast clipping off all the extra wire to use later. Now with every thing removed except the switch, I cut the strips so as many LEDs would fit where the tubes were. I think this worked out to be 21. There is no need to remove the ballast or the old tube holders/connection.
These strips have a cutting line every 3 LEDs which you must use. This terminates the strip section so you only need to wire one end. These strips are self adhesive and just stick to the fixture. On my first one I just put one strip on each side as a test. This proved to be not quite as bright as the original florescents, but we were very pleased and thought the originals were too bright anyway. My fixtures were wide enough that I could have put 2 full strips on each side if needed. What's nice about these strips are you can put as many or at little as you want to get the desired light.
Once the strips were in place, I used a very small soldering gun as these things are pretty small. At the end of each strip on either side is the + connection and the - connection. Since I had 2 strips, I just soldered 2 wires from the + and - side of the switch to both strips. You could also just wire the switch to one strip and solder 2 jumper wires from the other end to the other strip. I found I had more room on the switch end. Once done, I just replaced the ballast cover.
I found using all the old wire to be a PITA because it was 14 or 16 gauge, very stiff as well as way too large. I highly recommend using a much lighter wire!
As far as directional, my lenses were opaque and defused the light anyway. The only way you can tell these are LEDs, is you can detect the string of individual lights rather than 2 tubes of light. Certainly not offensive and after a day, we don't even notice it.
I also replaced all the incandescent bulbs with LED as well as the 2 CRT TVs with LED TVs. Last winter in Fl, I performed a test at the CG. Having only 2 6v T-105s and fully charged, I pulled the plug on the charger. We both took showers everyday, ran the Fantastic fan most of the day, watched TV probably 5 hours a day and basically did everything we would normally do. It took almost 3 days before the batteries got down to 12v. With the 12v LED TVs, we have no inverter and no need for one.