Here are the options that you have and what I feel is the best for each application. The 302 block has a fairly short cylinder which with the strokers pulls the piston out of the bottom of the cylinder causing more rock and wear. The 3.250 stroke is a better combination for longevity and street use. It does not pull the piston out of the cylinder as far at bottom dead center and it also has a longer piston with a better compression height and rod ratio. The 347 with the 3.400 stroke pulls the piston out more at bottom dead center and the rings and piston do not live as long as the shorter stroke package. If it is not going to get many miles over its life time and you are worried more about power they are fine but will need rebuilt sooner and may us a little more
oil. This has nothing to do with the pin going into the
oil rin because both the 331 and 347 have this do many SBC combinations.
We do a lot of the Dart Sportsman blocks with a 4.125 bore and a 3.250 stroke that also yeilds 347C.I. and this is the best way to go but the block is more money. These are just some of the things we have found out over the last 20 years of building these. You take what you have and try to build the best combination possible for the application. Good luck, Keith Craft