This is all very easy Oakerz with the port timing calculators available now(one at the bottom of the index page)
Take your barrel and measure the hieghts of your ports to the top of the barrel and then you can work out what the various rod lengths and stroke will give you. Unfortunately it doesn't take into account the deck hieght of the piston but you will get a good idea.
Be prepared to have your cylinder head modified for both compresion and squish to be able to achieve your required port timings.
