At 68, my max HR is probably around 165. I just hit 161 on a climb and could have taken it up a bit more. My LT is 148, meaning that I can hold that HR on a climb for about 40 minutes. That's about 90% of MHR, which I believe is fairly normal for a well-trained rider. VT and LT are normally about the same.
http://bfitsandiego.com/bfit/content...-quick-summary
Test results and OP's experience do not match.

OP probably does not have the endurance to perform the LT test in the forum sticky. I suggest an alternative which will be close. Warm up 1/2 hour at 120 HR, including an all-out 1 minute effort at 20 and 25 minutes. Rest for a moment, then restart the HRM and immediately go very hard for 10 minutes, attempting to reach MHR at the end of the time. LT will be very close to the average HR for that 10 minutes.