You can use the same pin for your prop and sust, but HCG is water based and the measurement is going to be very small. You will want to use an insulin pin for that. You can still inject it IM, you will want to do it in another shot. Plus it's water based and your gear is oil. Some guys do mix oil and water based gear, but I would suggest not doing that
When you are ready to run your mast and tren, let me know and I would be happy to help you map out your plan!