you can get any, I repeat any part for a 283 that you can get for a 350, 327 or anything else. Start watching my classic car on cable, they have new, high quality USA made engine parts advertised every day (not this chinese crapola that we are forced to buy alot). Crate engines area much more economical, AND they often have a warranty. Something to think about. I get parts at napa, they are a little high, but can always get the parts, even the weird stuff like GMC 305e big block v-6 parts.

64 & 66 GMC long fleetside 4x4
Cartwright, OK