Does it have the Integral Head?
I think a Stock Cam or RV cam would work, the smog problem is from if you have too much fuel dumping in there or the spark ain't hot.
What kind of 4 speed will you be running?
The cam needs to match the rest of the drive train. The Stock 250 won't be running much over 4,000 to 4,800 rpm.

That's my two cents. Now can I have my change? ha ha


250 Integrated Head / 1981 C-10 Pick up.