Yeah its called offset grinding the crankpins. You are never going to get much more stroke out of doing this tho unless it results in having a tiny crankpin that wont be very strong. To me seems like a waste of time. Besides i thought you had a budget? Doing this will probably mean custom rods and pistons and then you have to find a bearing that has the correct width and size for the smaller crankpin
Perhaps you are better off de-stroking the engine and revving it harder? Thought of that?