318 LA rebuild after losing a valve seat

On the KB SBM pistons, the eyebrows are about 5cc a pair. Which on a 318, drops your 8/1 compression engine to 7.64.
If you can get away with just one eyebrow at say 2cc, then your 8/1 drops only to 7.85 ; That comes to .2 of a point compression gain from the usual; the magic of math!
On a 318, Every cc counts; and each .010 of head gasket is ~2.15cc, and every 1* of later closing intake valve hurts her to the tune of more than 1psi of cranking cylinder pressure. And at a starting point of ~130 or so psi, it's easy to get into the death-spiral of falling pressure. Which makes the lower rpm lazy. Which costs you; engine efficiency, a hi-stall TC, and probably a performance rear gear. So it behooves you, in the interest of driving satisfaction, to keep the total chamber volume as small as possible. This goes double for fuel economy because low pressure is a factor of poor fuel efficiency.