How are you going to stroke an FL350R crank 14mm? The swing will be larger than the cases. 4mm, 6mm maybe, 14mm never. The 490 piston was used quite a bit to make big bore setups, but I don't know of a single one stroked that much due to it not being possible. In order to set port timing, you use a degree wheel on the crank. You don't have a crank so I doubt your port timing woule be right even if you could stroke it 14mm.