This sounds like Paul's technique, but the caution about the Q motor should be taken seriously. Paul ran his antifreeze through the motor several times in order to compensate for any isolated water pocket areas, which sounds like a very good idea. With the Q motor I think I would follow the advice given by this boat shop, it sounds like they may have learned it the hard way. Here is their info below for your reference
Engine winterization. These are the processes we follow here in Cincinnati, Ohio. We can have temperatures far below 0 degrees during the winter months.
1. Start engine and recirculate fresh water through the engine using equipment suggested earlier in this article.
2. Shut off the engine and empty the water out of the five-gallon bucket. Fill the bucket with non-toxic marine anti-freeze.
3. Remove the drain plugs from the exhaust manifold, (2) if a V-8 or a V-6 oil cooler is equipped, the engine block, or either side of V-8's or V-6's or on one side if a straight 6. If a Chris Craft V-8 with water-cooled generator, remove the drain plug from the rear of that.
NOTE: If water does not come out, take a small piece of wire and probe the drain plug area until you get the water to flow out. Reinstall the drain plugs. Now, start the engine and suck the antifreeze out of the bucket and into the engine. Have someone catching the antifreeze when it exits through the exhaust. Check the degree of protection to be at least -20 degrees below 0, unless the lowest temperature in your area exceeds this. You may need 8 gallons of antifreeze to do the job. If you have a Chevrolet 454, you'll need more.
4. When you have reached the desired degree of protection, run the antifreeze through again and while the boat is running at a fast idle, run fogging fluid through the carburetor until smoke is very visible through the exhaust ~ then shut it off. On flat head six cylinder engines, just remove the spark plug, put approximately 2 ounces of fogging oil in each cylinder, then put a towel over the head and turn the engine over several times. This process will coat the cylinder walls and valves.
NOTE #1 On Chris Craft Q Series engines, a large hex head plug in the top of the intake manifold must be removed and water must be extracted using a turkey baster. This process must be done prior to circulating antifreeze through the engine. If it is not done, the intake manifold will freeze and break.
NOTE#2 On inboard/outboard (I/O), you can make your antifreeze feed by drilling a hole in the bottom of a five gallon plastic bucket, insert a ¾ O.D. bilge pump thru hull fitting, a ¾" I. D. garden hose section with a garden hose male end, then insert that into standard Mercruiser/OMC, etc. ear muffs. Position the bucket above lower unit level, fill it with antifreeze after positioning the earmuffs on the outdrive. Position two other buckets either side of the outdrive to catch antifreeze as it exits the engine. Again, check the exhaust antifreeze to be at a level of -25 degrees to -30 degrees.