A recent ct head scan (no contrast) showed calcified carotid siphons, should i have further tests done?

No: That's an expected change at age 59. If you have symptoms of coronary insufficiency, you should have a stress test. If you have transient neurologic symptoms, you should have a carotid duplex exam. In the absence of sx, you don't require further testing. Optimize your risk factors: BP, cholesterol, avoidance of smoking; Exercise daily and eat a healthy diet.

Yes: If you have intracranial calcifIc arterial disease, you may also have extracranial calcific arterial disease. A carotid ultrasound would be a good idea. Also a cardiovascular calcium scan. If your brain arteries are looking bad, your heart arteries could also.