The way I understand it, the 307 is the piston to use because almost same as 250 except flat top and just a few thousands short of deck height. The 283 is not used because it has a shorter distance from pin to top of piston, therefore would be too short in cyl..

Am I correct?

Stock 250 piston is dished about .085" also.

What cam for street driving? Stock or a RV grind?

Thanks,

Just my Thoughts,
Walt