I hadn't really thought about the engines but, having had a quick study, I'd probably go with the EJ200, with options to upgrade to EJ2x0 Stage 1 & Stage 2 as they became available.
Reason 1: EJ200 is bigger than the Snecma M88 by 17.5" length & 1.5" diam but is smaller than the Volvo RM12 by 2.0" length & 6" diam.
Reason 2: EJ200 is only 92kg heavier (dry) than the M88 but is 66kg lighter than the RM12.
Reason 3: EJ200 puts out more thrust (both wet & dry) than either the M88 or the RM12 while being less thirsty than either of them.
Reason 4: EJ200 has a thrust-to-weight ratio of 9.31:1, as compared to the M88's 8.5:1 & the RM12's 7.8:1
Alterations to the Rafale would be quite considerable, but less than for the RM12, & the EJ200 could be slotted into the Gripen with only minimal modification.
Hmmm, have to think about how to achieve that in plastic.
In my RAM universe I see both types being built under licence by the CAC, which still exists, & the engines being manufactured by the latest incarnation of the GAF, CAST (Commonwealth AeroSpace Technologies).