If you know the 8 won't fit your car I suggest the 230 ci 6. Information and parts are easy to find along with web sites that offer lots of help on these motors.
People have put the long block six(25" head) in smaller 40's-50's PlyDos, which requires some minor mods but the 8 would require some major modification in my opinion.
On the other hand, if you can weld, have metal fabarication ability and good mechanical skills I suppose anything is possible. Did I forget to mention money too? !
