Chamber size for iron head stroker

Egr puts heat into the chamber. Heat burns more. GM went crazy in that and ran all their temps way up in over 200-230 ish

Dont take and railroad the thread with emissions talk.
Quench is great, smaller compact chambers burn faster, less timing squeeze it all central to the plug and watch the power go up.
As long as you can unshroud the closed chamber.. it's not really behind the open one..its the flow that is slightly hindered from valve shrouding of closed chambers.
Really small down-to-earth example would be a 273 head closed chamber 920 casting. They flow around 170 CFM. If you unshroud that chamber all the sudden they flow around 183 CFM, allowing more signal to the straight side of the port ,therefore carrying the flow up higher in the lift than would normally carry. Same for all heads. While some chambers ARE so compact it's hard to unshroud them enpugh... there in lyes the idea getting a better port attached to that chamber to realize the advantage. Though there may always be a trade off...you just have to exploit the flow potential to offset that when comparing heads. Regardless..
It's all just planning and more or less work depending on the path you take. I pushed 91 octane california gas on heavily ported open chamber j hesds to 188 cranking psi /high 8's dynamic, I used kb 356 milled them about .046 off the quench pad...and milled the open chambers about .050ish for a depth of .030 and 60cc.. so the piston took up the gasket and the chamber gave the clearance. Heads flowing a hair better than those/op's.. a beast that rpm'd just fine and would just leave behind any car at speed...hardly, if at all, hooked from a light.
Just do it right and it wont matter either way.