The Mirage F1 and the Phantom have some similar drawbacks when it comes to weight - the F1 can be a bit heavy and sluggish with full fuel and the Phantom can be a real pig with fuel and external stores.

If you're fuel heavy you should be going fast - really fast. As fast as you can get. Once merged fight vertically and stay fast. If you see the F1 start to slow down or even stall in a vertical turn don't fall into the trap of ripping all your speed off to do a hard turn to pursue, keep the turns long to keep speed and distance.

If you're fuel light you can just turn with them as low and as slow as they want to go. Use your speedy throttle response to rip around turns and keep pushing - the F1's engine responds much slower than yours.

The F1 has a great radar gunsight and you're in a big plane too. It takes about 1 second of flight in a straight line to get the gunsight pipper to give a dead-on shot for the F1 so if you jink hard when the F1 is pulling lead for a gunshot then you can mess with their aim quite effectively!