I'm starting to gather info for my fall project. I have a 283 in my '66 which is going to be replaced by the chevrolet 290/350 crate motor. Would I be able to use this original radiator for the new 350 motor?
thanks in advance
Absolutely but as mentioned above get it checked out by a trusted source.
If you don't know anybody or atieast know somebody who knows somebody then if it were me I'd run it then take the cap off and look for good flow while the car is running.
If you have that and the radiator isn't leakin then run it.
Reason I say don't take it to someone you don't know is because there are no shortage of unscrupulous vendors/repair shops waiting in the lurch for an unsuspecting uninformed person to come along to rip off.
Eg..." you definitely need a new radiator sir"
When that may not at all be the case lol