BTW: the math comes out nicely.
235 stroke 3.9375" ÷ 2 = 1.96875"
235 rod 6.8125"
Total deck - CD = 8.78125"
New stroke 4.125 ÷ 2 = 2.0625"
292 rod 6.76"
Total deck - CD = 8.8225", or only .041" taller than the original.
This is probably do-able with a slightly modified stock piston using a new .927" pin bushing.