At +4 mil stroker the bottom of the crank case has to be trenched about half the thickness it is from the factory. Also, the crankends can't be but so long and not hit the bottom of the cylinder so the cylinder would have to be raised to clear the crank off the cases. Also, the balancer shaft would have to go because the area of the case that seals between the balancer shaft and the crankcase would be gone.
CAN it be done? Anything can be done with a custom machine shop at your finger tips and an unlimited budget. Would it be worth it? No.
I mean, a built LA sleeve BBK with a +4 crank puts out like 50 hp. Why would you need any more than that?