B;
Yes It's better for a 'built' 250/292 engine with higher compresson and engine speeds. No doubt about it/that.
The question was about a stock 1958 235" engine. In that that engine's combustion chamber, a higher voltage isn't going to change a thing with that compression pressure.
The spark is going to 'jump' the gap when the voltage reaches/gains the ability to travel through the (PSI) weather the (max) is 18KV or 50. In this case, it will jump at around 10+/- which is 8KV less that the factory provided.
If you put a ($300) 50KV unit in there the law (ohms) is still the same. It will jump around the same (10K) voltage +/- because of the low pressure. Having it precision made is of no benefit at 2,000 RPM either.
Higher (compression) pressures/speeds require more electrical power. Same as the alternater, W/O a higher load/demand a higher current rating is of no value.
