I like to make the lowers pretty wide to take advantage of the flow through the piston windows; widening under the bridge primarily on the exhaust side and then making the transfer outlet a little wider on the exhaust side. Thus the new charge doesn't have to do the back bend to get to the exhaust (primary) side of the transfer port opening. Making sure the exhaust side entrance collides with the opposite at 1/5-1/4 the distance from the center of the bore to the intake side. Lay back the intake side opening till it's close the the ring locating pins (394 piston) or until you like the entrance angle (395 piston with central locating pins).
For the roof I like to make the exhaust side pretty flat, the intake side I like to angle up a bit. I'll open the exhaust side 2 deg before the intake. This is pretty much opposite of how they came from the stock, but I've been noticing more newer designed saws to come closer to this configuration.
I can't find any pictures of a 394 right now. I'll try to snap some as I'm porting two right now. For now here is a 2100, pretty similar transfer design.
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