Just got a 1956 235 to replace my old 216. The front mounting plate on the 235 does not have the holes in it. Can I swap out the 216 front plate? If so how do I remove the harmonic balancer and is there anything I need to be aware of or is it a simple job? I also saw a tech tip that recommends changing the valves so the new fuels don't ruin them. Do the heads have to be machined to do that or can I just change out the valves?