South Africa did so multiple times.
First they upgraded a Mirage IIIRZ to R2Z standard by replacing the 09C with an 09k50. Admittedly these two engines are very similar, unlike the 09B to 09C change Israel did, sharing aiframe mounting points and with other R2Zs in service they had a good template, but it was done with no French help mentioned.
They spliced together two Mirage F1CZs (one had the rear fuselage destroyed in a engine fire after hard landing, the other had the forward fuselage damaged also upon landing after dogfight damage. They grafted the good parts together. Speaking with those involved this was a tough challenge to crack and French input even in a clandestine form is never mentioned nor would they even have a process for such an event. SA could not afford the loss of the aircraft.
That re-engined RZ (836) was later damaged beyond economical repair and the airframe stored. Few years later the rear fuselage was used to repair a Cheetah D2 (originally a Mirage IIID2Z) which had the rear fuselage destroyed with a hatd landing and engine fire. Again the two fuselages were grafted together. The Mirage F1 project some years before was quite helpful.
The biggest challenge was the SMR-95 project where a modified RD-33 was installed into a Mirage F1AZ and a Cheetah D2. Dassault in this case even said it couldn't be done (I thus assumed for this project they were approached to help seeing as this was during the period South Africa was starting to move into democracy and this was an even tougher nut to crack than previous rebuild/reengine projects in the sanction years). But they managed it and flew both prototypes very succesfully.
Dassault and Snecma were happy to clandestinely supply engines though through middlemen and I would assume certain spares too. SA was still investing in its aviation industry and all the related supporting industries and could only do so clandestinely thus lagged behind Israel there who could openly get help there. That is why local production lines of new built fighters (even with Mirage F1 plans from Dassault at time of purchase resulted in no new built aircraft).
I guess it would be foolish to state none of this had any input from Dassault as they plausibly at least consulted clandestinely, but in especially the Cheetah project they lacked data that Dassault could have provided but didnt like aerodynamic data around the rear of the aircraft and thus had to work more creatively like when designing the ventral fuel tank integral chaff/flare fit they used the RATO pack outline as guide within which to work. The Cheethas used differerent designs here than Kfir.
