Dave,
The 289 and 302 block both have the same deck height and are virtually the same to answer the last question. Does your engine block have the VIN # stamped in it? I did not see you say that.
I can do some research, but to stroke to 347 on the 8.2 deck height of the 289 and 302 may require some minor notching to the bottom of the piston liner to clear the rod end caps. Not sure for the 331. This notching is minor and not a problem for longevity. The new 347 stroker kits have improved the piston pin location to allow for better oil ring sealing. The first 347 strokers had oil ring issues....
Rob, great information. Thanks. Roughly, where along that spectrum of changes could you get an additional 60hp from a stock J-code engine w/10:1 compression (240BHP -> 300BHP)? A swag is fine... I'm just curious...