The single flat next to the centre head bolt on the manifold side makes it a 73+ head like Eric said, A/B/E/F they all have an improved exhaust port that responds much better to porting due to a larger SSR. It is 1st choice for a maximum port job because it has meat in the inlet ports that is hogged out in E/F heads. It is 1st choice for strokers too.

Compression depends what octane fuel you want to use.

"I know that my block will never have the best flow given that the cylinder bore will not match the head."

92mm front to rear combustion chamber doesn't match an 88.9mm B20 either! You just need to use a B20B/E headgasket when you bolt it on. Later you can bore your B18 to B20, or put it on a B20, I would not touch a B18 head unless you had to. Some historic races might force you to use a B18 head, but that limits valve sizes.

With the K cam, which is one of the only cams to use with stock springs, any head with a decent valve grind will work because the inlet doesn't actually open high enough to use the flow figures from a ported head. I wouldn't let anyone port the exhaust unless they are B20 experts, because it is far to easy to take meat out of the wrong place & ruin it, just a proper valve grind & back cut the valves.