Coolant level question

[wpavlis]

First off, thanks to everyone who has answered my many questions in the past. I fired up the new 350 that i just installed in my 68 c10 today. During break in as the motor came up to temp the radiator puked a bunch of water. Temperature was fine bit i checked and from what i could tell everything was fine. Finished the break in and temp held rather steady the whole time. When it cooled down i checked the coolant in the radiator and it was an inch or two low. I filled it back up and took a quick test drive around the block and it puked some more coolant again.

Now to my question. Is this normal on an open system? I have never owned a vehicle without a coolant bottle. I am guessing this is just the system equalizing and if i had a coolant catch bottle it would get sucked back in as the radiator cooled back down. Does that sound correct? Thanks again for all the help and advice.