The fixture is ok but be sure to measure twice, or three or four times, and cut once. I find that using a caliper worked for me to plot out the critical measurement for the relocating of the bobtail housing hole in the frame. The Brown bobtail is a really nice piece with extra material to blend into the sides of the frame. Top notch stuff!
just a drill press, used a #2 center drill (actually a #2 countersink) to start the hole. yes, did the grip panels myself, just a bastard file and then some 200 grit sandpaper to finish the surface, wood stain to match finish.
spent most time and sweat trying to position the mainspring jig and frame properly. The ed Brown drilling jig worked well, but a real table with T-slots and a step block and clamp set would've made life easier then my collection of crappy C-clamps...
congrats. radar's suggestion about measuring twice, and then a few more just to be sure, is well put. my biggest problem was clamping the jig and frame to the drill press table so they were really rock solid without moving the jig (and frame) out of alignment with the drill. if you've got that really locked down, you should be fine. post some pics when you're done!