that would be your best option

Resource leveling using different calculation engines is a sure way to create mismatches, for this reason using different software to manage schedule and to manage risk does not makes much sense.

The differences can be very big.

https://www.stottlerhenke.com/wp-content/uploads/2011/09/2009-10-01_Auro...

• In this paper we have shown that resource constrained schedules and therefore resource constrained project management is greatly affected by the underlying resource-leveling / scheduling engine more so as the project becomes larger and includes larger numbers of resource requirements and other non temporal constraints. It is unfortunate that project teams that have put in the significant effort and cost to create a resource constrained model may not know that they could potentially reap huge time and cost savings simply by running there already built model through a different scheduling engine.

By the way if using Spider Project out of the box, without need to look for prioritization rules we get better results than Aurora, P6 and MSP on the eight activities sample schedule, we get the optimal solution.

I think there is no solution for your problem.

The available leveling options for MSP and P6 are very different and cannot be perfectly aligned.  In addition the leveling rules for MSP are essentially a black box.  You may be able to introduce some preferential logic into your P6 schedule to mimic the MSP leveling decisions.  Even if you could get perfect alignment between the two tools in a baseline schedule, this alignment would disappear at the first update.