There are reasons for everything... simply sticking misc part designed for stock stuff into a hole they will fit in is not always the best course of action. In the case of pistons... some numbers that might clarify.
stock 400 stroke (3.38"):
mean (average) piston speed at 4K= 2253feet per minute At 5500rpm= 3098FPM
Max piston speed at 4K= 3648FPM At 5500rpm= 5016FPM

4.15 stroke:
mean piston speed at 4K= 2756FPM at 5500= 3804FPM

Max piston speed at 4K= 4500FPM at 5500= 6200FPM

The reason cast pistons are not part of stroker kits is because they simply are not designed to withstand high acceleration and deceleration rates the longer strokes create. almost 25% more max speed, but accelerated and slowed down in the same distance. The pistons will simply flex for a while, then either the rings begin to lose seal as the ring lands deform, or the pin rips offf the domes. You can help the mean average speed by keeping the peak rpms down. But you can't drastically affect the rate of acceleration because of the stroke. So, you have a package that limits lift because of valve reliefs, and rpm due to materials. I understand the "do it because I think I can" mentality. But truthfully, I dont see why someone would want to unless you have a full machine shop to play in for free. Then it might be fun to see what could be done.