Stock valve guide size X heads

Good day to all. I have a 360 engine with stock X heads. My valve springs are getting weak and I'm planning to replace them. I have dual springs on it that matches the roller cam setup. I was wondering what is the valve guide size. It's been years since I've had the engine built and having difficulty contacting the engine builder. My car is in The Bahamas and I'm trying to order the right parts before I go to fix it. Any help would be appreciated. Thanks in advance.