216 cu. in.
year numbers block casting numbers
37 1 to 1187821 838101
838710
38 1187822 to 1915446 &
B1 to B10502 838710
39 1915447 to 2697267 &
B10503 to B105461 838941
40 2697268 to 3665902 &
B105462 to B229135 839132
41 AA 1001 to AA 1163720 &
AC 1001 to AC 19549 839400
Check 1940 in the chart. According to your number you have a 216, Get a new friend.
Choices depend totally on what your son wants to REALLY use the car for. Sometimes the hardest thing is to be honest with yourself. One car can't do everything racer, driver, show car. No matter how much time & money he expends it is only "stock" once. It can be restored to stock specs but that is not truly stock. Often a solid survivor is far more interesting than a perfect rebuild based on foreign made reproduction parts.
The 216 is a much maligned engine and is far better & stronger than its "babbitt beater" nickname would lead you to believe. The biggest issue would be finding someone who could repour the bearings if needed. There are ways around that. stock49 here is very knowledgable about these engines a new arrival is proposing some radical new mods that bring the 216 into the 21 century,
The 250-230 swap is not a bad idea, It is not difficult and parts are much easier to find as are people who know how to work on them. They could make it perfectly capable of present highway speeds and there are many performance options. There are also the "traditional" 235-261 and the GMC family or even a 292. There are lots of choices before he gets to the V8 things. Again an honest assessment of what the car will really be asked to do is crucial.
So the choices are many and it depends totally on what the 17 year old wants to tackle and what he (and those around him) are capable of. It doesn't all have to happen at once. Many of our builds evolve as skills and resources evolve. A real " hot rod" is never finished. He could be one of those guys who still has his '40 when he is an old man. Sorry for the rant, Good Luck kid!
