I have had HBP since I was a teen, and didn't get it under control till I was 25. Actually, my doctor was wondering why I wasn't passed out and heading to the hospital when I was placed on the meds; it was that high. I have never had a problem going on any of the rides before, or after getting it under control with the proper medication. I would also, as other people have mentioned, consult a doctor to be safe. My personal rule of thumb is that if I am feeling iffy, I will pass on any thrill rides till I start to feel better. My comfort level with the rides at Disney is extremely high, but that is just me. Usually if I am feeling iffy it is more to do with the heat and humidity. I find a place to cool down, and rest for a bit. (Long slow ride, or someplace to grab a quick bite to get a drink and sit inside) After the feelings subside, I am usually able to get back to the thrill rides.
My recommendations would be:
#1 Ask the doctor
only if the doctor says that it will be alright #2 Listen to your body (Feeling lightheaded, pulse quickening, shortness in breath, palpitations, just stay safe and relax and take a break)