Is it worth drilling the hole in the block and water pump for the water pump bypass feature introduced in 1953? I am rebuilding a '47 216 and its time to mount the water pump.I can get the hole location from a newer model gasket.

Bypass hole in the block, introduced in the 53? What do you need it for in a 216?

The by-pass, never used on a 216, is probably more important in cold weather, like below freezing temperatures. On a 216 the thermostat opens fast as the engine does warm up quickly.
You could probably get the same benifit by drilling an 1/8" hole in the thermostat (or a little larger). Other than that if you were to drill a hole in the block it would be important to see that the hole isn't going into an area that could cause damage.
To be honest I have thought about doing the same on my 1950 235 block.

i think drilling a hole in the t-stat is a better idea.
i have been doing that for years on all my cars. works great when the t stat opens you don`t get that burp of coolent out the filler neck.

Thanks guys for such a quick reply.I will drill the 1\8 th hole
in the thermostat. regards Paul.

yep, that is a better idea (drilling the flat place on the thermostat) and then if you get a chance to move South to God's country, you can just buy another thermostat!

....... just kidding about buying another thermostat!
Send us some pictures of a real snowman if you see one,