Yes they both have 4 inch bores but if the chamber size where the valves is different it will change the compression.
If you are asking if you can substitute a 350 for a 305, the answer is generally yes.
No. The bore size is different between a 305 and 350. The 350 bore size is larger.
Yes. Its a direct bolt in.
The cams interchange.
No
yes
305 is the same distributor as a 350 will even fit some big block chevy's.
YES.
YES
No
yes
Who said it won't ? It will fit right in there with NO problems