[sclor]

Nut:
I'll take a crack at your question. Others feel free to embellish.
* 351e is a magnum with bigger valves, bigger intake and exhaust ports.
* 351 has larger bore than 305. I believe it's 4.25" for 305 vs. 4.5" for 351.
* 351 has steel crank vs cast crank in 305. Unsure about stroke?

Hope that helps.
Regards
Steve
New Orleans