“I'm currently running a Boyer
ignition on my '76 T140V. No complaints, it performs just as well as the stock points.”
As the stock points and EI end up at similar advance above ~4k or 5k rpm, you shouldn’t notice much difference at higher rpm.
It is at lower rpm that you will notice a difference.
Points/AAU will reach full advance at lower rpm than Boyer
(and most other analogue EI).
Typically points achieve full advance ~2500rpm, typical analogue EI’s ~4000-5000rpm.
If running a sporting engine (say ~9:1 compression) the more relaxed curve of EI may help avoid detonation at lower rpm (especially with modern fuel).
All ignition systems should provide the spark at the same timing at high rpm (which is where you say is where you are losing grunt).
Changing the advance curve won’t change this, it can only change how it performs at lower rpm.
Listen to the folks experienced with cam timing, that can change where your engine buzzes.
One thing I have used are the simple old fashioned Megaton reverse cone “silencers”. They make a Triumph truly fly. Avoid the cheap look-alikes, they don’t work.