Rotary heads and popups typically operate at a considerably higher pressure than you want for a drip system. You don't say what the capped stub is made of or the size. If it's PVC (white pipe), you could put a fitting on the stub, screw in a pressure regulator (preset, 30PSI...$7 at Home Depot), and then attach the appropriate fittings for the dripline to the outlet end of the pressure regulator.

Generally rotor heads have other heads on the same circuit. This means that the drip zone would only run as long as the rotor zone. Drip generally runs a long time and a rotor can run a medium time 30-60 minutes.

How were you able to remove a head and not produce a dry spot?

garden-guy:

The area in question was formerly turf that I converted to a shrub/perennial bed. Now I'm looking to set up a dripline in that area.

what I've done when converting riser to drip is buy a manifold at a irrigation supply house. they look like a mushroom with drip tubes coming off the bottom. the maifold must have built-in pressure compensation and a filter. your challenge will be matching the minimum flow of the vavle (I'm assuming the zone is on a electric valve). Most valves have a relatively high minimum flow (GPM) and the flow from a single drip head will have to be at least as high (GPH). A good valve will be down at around .1GPM. I'm sure you don't want to change out the valve so the alternative is to match the minimum flow out of the drip. I also recommend putting the manifold in a hand valve box with the top of the box slightly above grade. Good luck