Just thinking out loud and maybe way out of the box but am wondering if a low riser head would benefit with a valve angle closer to what the original SBC had at 23 degrees. Just thinking that flow through the port itself would benefit. Could be that after it gets past the valve the flow at larger valve openings would be shrouded more but the increase in flow through the port at lower openings, because of the straighter shot, might offset that. Thinking more for street use at lower lifts.
Just thinking that the original SBC at 23 degrees performed so well for so many years and while decreasing the angle to 18 degrees and finally, I believe, to 13 degrees ( same as all FE's?) did increase performance it also required raising the ports and manifold to take advantage of the smaller valve angle. This was the reason for the medium and high rise FE's. Raising the ports was simply taking advantage of the already small FE valve angle. A larger valve angle would let the already low ports on the low riser heads and manifold perform better.
Probably backwards thinking and probably not even feasible especially when talking of compatibility with the traditional FE shaft rocker system. Not even sure of a market for such a head although there may be more users that would want something that may perform better for street use and still fit under the hood. I know most medium riser setups will fit under the hood but they might also benefit from less of an angle (18 degrees?) in certain circumstances. Probably would take some fancy mockups on a flow bench to prove or disprove.
There is still a market for 23 degree SBC heads even though the 18 and 13 degree versions have more power potential.
Am I way out of the ballpark or just in left field? Most likely this subject has already been talked about (most likely when Edelbrock was developing their FE head).
Thinking further (I get in trouble every time I try that) the traditional, half of a head, FE architecture probably would place the rocker shaft pedestals into the manifold side of the head for a rocker system that would be compatible with anything more than the current angle. Probably why it's never been done.