Opening the throats to 90% of valve seat diameter is important, nice ports won't show much flow improvement without doing it. I'd have a real head shop / porter guy handle this, the job gets done correctly and the results will speak for themselves.
Zero decking the block will give several benefits as well. George Bryce wrote on this years ago as a primary source of otherwise missing horsepower. An example big HP Comp motor benefitted by 15 HP... so I would take his word for it.
I don't have an answer for the SOHC chamber style based on any dyno results, only what others far smarter than me have shared.
A hemi head exposes alot of surface area but unshrouds the valves. RC did lots of 'em and I have one too. I also have had ported stock style heads that ran great. More important to remember is that 200+ psi
cranking pressure always wakes up a motor. I ran 240 psi on 93 unleaded - tune carefully.
All the 4 wheel drag stuff I've played with have hemi heads (well, except the jet) and I figure since Allen Johnson, Brad Anderson, Minor Bros, etc make the chambers that shape... One motor has 6.3:1 CR, another has 12.4:1 CR. Different applications & fuels, but both hemis.
Do the math before grinding.
Again this is all just my .02