Struggles after 4900 rpm

Now that you have bumped up the initial to 19btdc you might be running more than the max 34-35 degrees with full mechanical advance, if you can I would invest in a timing tape to make sure you are not exceeding the 34-35btdc at 2500rpm (mechanical advance all-in).

I intend to do this as soon as possible. I have also set my initial to around 13 now, but with the same result.

If you have the vacuum canister hooked up then you shouldn't exceed 50btdc at cruise speed (part throttle, high vacuum with timing all in). Too much advance might result in detonation and you can't always hear it.

Is detonation the same as pinging? Sorry, but I dont know that word. I'm from Sweden :D

Have you checked the spark plugs for any sign of detonation?

Since you changed a few things before this happened you can always change individual items back to how they originally where just to check if any of the items are bad. Old spark plug wires can look good but miss or spark-over at high rpm. Just a thought.

Good luck.

How will they look if there is detonation (that word again)?
Thanks for all the advice and suggestions, I will look into all of them!

Any chance this could also be related to the coil?