I found out some info today on radial orientation. Single row engines are mounted with a cylinder straight up at the top (#1) Twin row have the rear row oriented like that, and the front row, being offset for cooling, will have a cylinder straight down. I was looking at some engine pics and noticed a P-47 had its engine "upside down", until I did some reading.
And whichever way the engines are oriented, oil still collects in the bottom cylinders. On 7 cyl. engines, that is #4 and #5, and on 9 cyl, it's #5 and #6. Recommended practice for start-up is to pull the engine through two complete revolutions to clear the oil. If any resistance beyond normal compression is felt, the front plugs must be removed and the oil drained from those cylinders. A small amount of oil may not cause any resistance,and gets blown out at start-up as blue smoke (dry start) or oil droplets (wet start); but if enough collects to fill the combustion chamber, a hydraulic lock occurs, and if the engine is forced through the lock, severe damage can occur, from bent connecting rods to complete separation of the cylinder from the block. Try this site, great reading for radial buffs:
www.radialengines.com There is a menu to select from, and a number of articles in pdf format written by one of the mechanics/engineers. This company is the formost rebuilder/overhauler of small radials in the US