But the cost needed for a stroker crank, truing and welding (not sure if Blasters need that), good bearings, all seals, gaskets, etc., the cases may as well be trenched. Compared to the existing cost of the build, there'd be no reason to stay with a 3mil. Only extra cost that I'd see would be case trenching and a custom dome (I'd recommend that for any 2-stroke).
I was shooting for the 60whp range from my Banshee and it was strongly impressed upon me that I should have my crank trued and welded before then. The cost for that would have been around $360 for the place that I chose to do it. I'd planned on going with porting and custom domes, so the only thing that stood between me and a 4mil would have been about $90 ($450 trued and welded 4mil). I'm setting aside $1700 for a full teardown and build. If I was going to spend $1600 for a stock stroke, may as well drop another $100 for even more power (shooting for 75-80hp now).