comparison of combat jet engines

I’ve been looking into the modern jet engines that all the combat jet engines, from the days of the century jet fighters. I’ve always wondered, what’d be like if we were to place a J79 into Panavia Tornado or F404 into F104 star fighter, for example.

Tab data comparison for these engines give some interesting contrast.
For example, Specat Jaguar uses “Adour Mk 102 turbofans” that produces only 32.5kN, that gives the craft only about 16,000 kg take off weight.
A general electric F404 turbofan can produce 85kN trust in comparison.

Naturally, size and fuel consumption is all major factors and in the case of the Specat Jaguar, for example, Adour Mk102 is smaller and 809kg, whereas F404 is 1034kg and almost double the size.

But surely a good trade off can be made in many combat jet fighters, by placing a newer and better engine. An F404 engine inside Panavia Tornado could catapult the tornado to much superior characterstics.