Welcome to the site!
The Good Guys '32 coupe is a sweet little kit, great to get back in the game with, so to speak. Everyone has their own way to add plug wires, and hopefully some others will post theirs.
Here's what I do: I use 30awg "wrapping wire" from Radio Shack. It's a single strand, jacketed wire that looks "right" for 1:24 and 1:25 scale. It comes in red, white, and blue (God bless the USA!), and the jacket can be painted if handled lightly. For the plug boots, I strip the jacket from a slightly bigger wire and cut to short lengths. To drill the holes in the distributor, coil and cylinder heads, I use a #75 drill bit in a pin vise. A small drop of CA (super glue) holds the wires in place. First, make sure the distributor posts are large enough to drill without splitting them. If not, file them down a bit so you have enogh material to drill into. Drill the holes approximately 2-3mm or 3/32" deep. Attach the heads to the block, and drill the holes where the plugs would be. You may want to go ahead and drill through the block so you have some "wiggle room" to get the length of the wires right. Cut eight lengths of wire, a little longer than needed to reach the cylinder furthest away from the dist, then attach them to the dist. If you are going to add boots, then make eight of them, and slip them over the wires. Start running the wires to each cylinder, making them look as natural as possible. Cut the wires a little longer than needed, and isnert them into the plug holes. Once you have the length correct, glue the wire in place, and slide the boot in place. Here's a flathead I did using this method:
Hope this helps,
Brian