i got a 74nova and plan on using the engine but i cant figure out if its a 350 or 305.the only numbers i can get are v0913tpa.and those are perfectly clear so i know those are correct. i got these off the block by the water pump.down by the engine mount on drivers side i got 688 or 633 they were pretty bad looking.and i saw 16551n around there also.and what is also strange is the vavle covers bolt on in the middle to the heads.not around the sides.the vin number is 1y27h4w237996 but the pervious owner said that wasnt the orginal engine.if u guys can help me or give me a step by step to geting the casting number.pics are worth a 1000 words.thanks