I use a timing light to check the timing before running my car. I would not be afraid of the cast crank. Cast pistons would be a different story.
The idea to add a retard switch is a good one if you are fooling around on the street. A pressure referenced bottle heater is a good idea too.
FWIW I ran my 68 GTS at a no prep event a few weeks ago. I was leaving at 5k rpm ramping in a 125hp kit from 80% in .5s on a 235-60-14 tire.
You will be suprised what you can get away with if the chassis is right. My car responds better to more power up to a certain point.
PS my 451 has bushed LY rods and the axles it was born with.
