I'm not a physician, don't play one on TV, and certainly don't get paid like one either :-)
Unfortunately there is no good correlation between heart rate and blood pressure. Suppose someone had high blood pressure - well taking their pulse would not be a good measure of what's going on with their BP.
It is interesting because when we all exercise for example, no doubt heart rate goes up...significantly and even to maximal levels (in the case of hard L5 work). Yet that faster beating heart, doesn't cause your blood pressure to increase at the same rate.
Let me give you an example...my resting HR is about 40. Ok, well you can easily double, triple, possibly quadruple that HR (as compared to resting) during hard exercise...I've seen 170+ during L5 work. Yet there's no way blood pressure will increase anywhere near that, meaning a 3-4 fold increase...
If you need rest, then take it. However I'd also say, at least in my own experience with hard training, that there are times when you can push through quite a bit of soreness & fatigue if you pace a ride properly. I've surprised myself more than once on the 3rd or 4th consecutive day of a hard block of training when I expected to have very little left but ended up doing rather well. Usually RPE is higher but you still have the capacity to do a great deal if you dig deep...