You really should consider babying your '87's electical system.
The '87 lighting coil was designed to power one 35w bulb at full rpm.
Depending on the "look" you're trying to acheive you can go with a larger round or square headlight with a bigger reflector. This will give you a broader, further reaching light pattern for the same 35w. In effect it "feels" like a brighter bulb. If you're gunna go with the smaller 5" Bates type headlight you'll probably get even less usable light than the stocker.
TThe horn doesn't present quite the same issues as it runs off the battery/charging system. There are several threads concerning upping the horn output and installing horn relays, etc.