Calf soreness is perfectly natural when switching to a forefoot strike. As long as you run with some regularity, it shouldn't be a problem for much longer.
Think about it. Have you ever heard of folks complaining about how women's legs and feet get all wonky from constantly wearing high heels? It's because raised heels shorten the Achilles and it actually atrophies because it is prohibited from a full range of motion. All the shoes we wear today are lifted in the heel, thereby atrophying everyone's Achilles (and other related muscles and ligaments, etc.) to varying degrees.
The Achilles tendon is not a muscle and can't be stretched out quickly. This will take time to undo all the years of abuse. Trust me, I know. I've been at the forefoot strike and barefoot running now for a little over a year, and my calves still occasionally get sore. If you're a runner who's used to high mileage, please promise me that you'll take it easy with the forefoot stuff for a few months. Otherwise, you might be one of those folks who gets injured right outta the gates and declare that forefoot striking "doesn't work for me". When your muscles are "sore", this means your joints are at risk because they don't have the normal support they require to hold them together properly. So don't overdo the stretching when you're sore! This may feel good in the short term, but it's actually counterproductive. Let it heal before going out hard again.
It will also help to go barefoot as much as possible elsewhere, at home, in the garden, etc. I've also begun switching out almost all of my shoes to ones with zero or little drop.
Welcome to the wonderful world of forefoot striking! Be sure and try some actual barefooting to refine your form. Can't fake it when you're barefoot.