My guess is that unless a person is building a high end motor like pro stock or a " class" type motor this stuff is best left in the hands of an accomplished head porter who is armed with the basics of a combo and it's intended use.
The longer the stroke with a given head the lower rpm a motor needs to be spun to make peak horsepower, and peak torque will come in sooner as well.
I would plan the combo around how much you plan to invest in valve train components, and how long you want the motor to live. Those will dictate how big an arm can be used with the intended head.
All the above assumes the OP isn't building a pro stocker or a trick " class" car