Not done this myself, but I would recommend you do some research before "simply delid the CPU..."
I believe it takes a tool if you want to reduce the chance of killing the CPU, and even then the chance won't be reduced to 0% -- meaning you might literally turn your 4770 CPU into a paperweight. You also have to remove the black adhesive with a razor and its apparently very easy to knock a cap off the die.
You could try a better air cooler on the 4770 if you had room for it in the case, but supposedly running at up to 90c is feasible on that chip without degrading it's performance. And unless you are slamming that CPU it won't generate much heat just running
Blue Iris and pfSense.
To get it closer to the 3770 you will probably have to do something exotic, unfortunately, or live with it the way it is currently running, and just plan to replace it in a few years if it breaks down (by then 8700/9700's will be cheap).
*correction* see here:
The Intel 9th Gen Review: Core i9-9900K, Core i7-9700K and Core i5-9600K Tested seems they all are paste, none with pads. But Coffee Lake Refresh (9700/9900) is supposed to be soldered again.