There's information else where on this forum that discusses the pro's & con's of altering the 370's suspension travel. The one thing that can be done to destroy a RM370's handling is to lift it. When we met with DeCoster, he talked about the way that Suzuki went with the 400C and more-so the 400N & 400T with the increase in suspension travel that diddn't translate into better handling.
As the 370 is a Pre78 legal bike, changing the stroke (increasing it) will push it to an EVO class and it's not going to be competive in that class against the hybrids that exist there.