Need help decoding an engine

[Blade]

Hello I have a Boat that my father built in the 60's. I was always told that it has a 300 Buick in it... Well. it has the aluminum heads with cast iron block and 4 bolt valve covers .. so one would think that it is a 300 1964...
Well in the drivers side between 2 plugs there is a milled off spot that has the code PO73.. this tell me that this is a 350 from 1968...

Is there anyway that I could have a 350 block with 300 heads on it?? or is the PO not a 350 only.

Are there other places to get numbers to decode what I have??

Block has 3 freeze plugs per side, if this helps any...


Thanks for all the help

[bob k. mando]

Is there anyway that I could have a 350 block with 300 heads on it??

the 350 had a changed valve order and cams were not (normally) interchangeable from the 350 to the earlier small blocks specifically to prevent people from accidently using a cam in the improper application.

check your casting #'s on the block and intake. if this is a 350 block they had to have used a 340 intake in order to mate the intake ports on the heads...

you can pull a spark plug and insert a ~2ft length of wire to determine the actual stroke of the crank. of course, you'll have to take the crank around one full rotation and locate TDC and BDC.

the heads being aluminum tells you that they must be from either a 215 / Rover or, as you say, the 1964 300.

http://www.buicks.net/shop/reference...g_numbers.html

http://www.gesslerheadporting.com/me...a!OpenDocument