Looking on the masters website is great, but those workouts are designed for swimmers. I have done both for a while, and have a few tips:
-I don't know your swimming ability, but either way id say stick to freestyle and backstroke. There's not too much of a difference in the strokes in terms of work that relates to running, but poor mechanics in butterfly or breaststroke can lead to overuse injuries.
-Similarly, don't worry too much about swimming-specific things, such as flip-turns. Get your legs, core, and lungs working hard so they can do it better on the trails and tracks.
-Focus on breath control. try breathing every 3 or 5 or 7 strokes, even if that means going slightly slower. This will help aerobic efficiency in running.
-This is going to sound weird, but try kicking from the hips, and having the motion travel down the leg almost like a whip. You'll work your legs pretty hard, and get some good speed in the water.
-Try to keep your hips up by engaging your core. It works your core, helps overall posture (both swimming and running), and will have you swimming faster.
-If you have a favorite interval workout that you do running, adapt it by dividing the distance by 4. I.E. repeat miles would be repeat 400's in the pool
I know this is a lot, but i really like seeing runners get in the pool, but there's a lot they need to know other than "Just swim." Let me know if you have any questions